21st Century Scientists

Vote for Your Favourite 21st Century Scientists

Right IconThis ranking is based on an algorithm that combines various factors, including the votes of our users and search trends on the internet.

 1 
Stephen Hawking
(Theoretical Physicist - First to Set Out a Theory of Cosmology)
Stephen Hawking
126
Birthdate: January 8, 1942
Sun Sign: Capricorn
Birthplace: Oxford, England
Died: March 14, 2018

Stephen Hawking was an English theoretical physicist and cosmologist, who despite being afflicted motor neurone disease that severely limited his physical abilities, was able to build a phenomenally successful career. He was the first to set out a theory of cosmology explained by a union of the general theory of relativity and quantum mechanics. Hawking was ranked 25 in the BBC's poll of the 100 Greatest Britons, in 2002.

 2 
Neil deGrasse Tyson
(American Astrophysicist, Planetary Scientist and Science Communicator)
Neil deGrasse Tyson
98
Birthdate: October 5, 1958
Sun Sign: Libra
Birthplace: Manhattan, New York, United States

Public Welfare Medal-winning astrophysicist and academic Neil deGrasse Tyson hosted shows such as NOVA ScienceNow, Cosmos: A Spacetime Odyssey, and Star Talk. He is the director of Hayden Planetarium and contributed to the dismissal of Pluto’s status as the ninth planet. He has also written a monthly column as "Merlin.”

 3 
Richard Dawkins
(British Evolutionary Biologist Who Contends that a Supernatural Creator Almost Certainly Does Not Exist)
Richard Dawkins
34
Birthdate: March 26, 1941
Sun Sign: Aries
Birthplace: Nairobi, Kenya

Richard Dawkins is a British ethologist, author, and evolutionary biologist. He first achieved popularity after publishing his book, The Selfish Gene, which is credited with popularizing the gene selection theory. The book is also credited with introducing the term meme. In 2006, he established the Richard Dawkins Foundation for Reason and Science to promote secularism and scientific literacy.

Recommended Lists:
 4 
Tim Berners-Lee
(Computer Scientist and Inventor of the World Wide Web)
Tim Berners-Lee
28
Birthdate: June 8, 1955
Sun Sign: Gemini
Birthplace: London, England

Widely known as ten inventor of the world wide web, Tim Berners-Lee made the first communication between an HTTP client and server through the internet in 1989. He is associated with various organizations, such as the W3C and the World Wide Web Foundation, and has received the knighthood, too.

Recommended Lists:
 5 
Grigori Perelman
(Mathematician)
Grigori Perelman
16
Birthdate: June 13, 1966
Sun Sign: Gemini
Birthplace: Saint Petersburg, Russia
Russian mathematician Grigori Perelman is best known for his work on geometry, especially Riemannian geometry, geometric analysis, and geometric topology. He declined many prizes, such as the Fields Medal and the Millennium Prize. His proof of the Poincaré conjecture was named the Breakthrough of the Year by Science magazine.
 6 
Vint Cerf
(Computer scientist)
Vint Cerf
13
Birthdate: June 23, 1943
Sun Sign: Cancer
Birthplace: New Haven, Connecticut, United States
Recommended Lists:
 7 
Terence Tao
(One of the Greatest Living Mathematicians Who is Referred to as the 'Mozart of Mathematics')
Terence Tao
20
Birthdate: July 17, 1975
Sun Sign: Cancer
Birthplace: Adelaide, Australia

Terence Tao is an Australian-American mathematician who works at the University of California, Los Angeles as a professor of mathematics. Widely considered one of the most prominent living mathematicians, Tao was honored with the prestigious Fields Medal in 2006. In 2014, he was awarded the Breakthrough Prize in Mathematics.

 8 
E. O. Wilson
(Biologist)
E. O. Wilson
10
Birthdate: June 10, 1929
Sun Sign: Gemini
Birthplace: Birmingham, Alabama, U.S.
Died: December 26, 2021

E. O. Wilson is an American naturalist, biologist, and writer. An influential biologist, Wilson has earned several nicknames, such as The Darwin of the 21st century. He has also been referred to as the father of biodiversity and the father of sociobiology. In 1995, he was ranked among the most influential American personalities by Time magazine.

Recommended Lists:
 9 
John Horton Conway
(British Mathematician Known for His Contributions to 'Combinatorial Game Theory (CGT)')
John Horton Conway
14
Birthdate: December 26, 1937
Sun Sign: Capricorn
Birthplace: Liverpool, England
Died: April 11, 2020

Remembered as versatile mathematician, game wizard and polymath, John Horton Conway had limitless curiosity, which matched with his scientific originality. Although he is best known for devising the cellular automation called Game of Life, he made significant contributions to group theory, number theory, algebra, geometric topology, theoretical physics, combinatorial game theory and geometry. Conway published many outstanding papers in these fields.

 10 
Alexander Grothendieck
(French Mathematician and a Pioneer in the Field of 'Modern Algebraic Geometry')
Alexander Grothendieck
10
Birthdate: March 28, 1928
Sun Sign: Aries
Birthplace: Berlin, Germany
Died: November 13, 2014

Alexander Grothendieck was a 20th-century mathematician who was a leading figure in the creation of modern algebraic geometry. With his so-called "relative" perspective, he revolutionized many areas of pure mathematics. During his later career, he became a professor at the University of Montpellier. He is counted among the greatest mathematicians of the 20th century.

Recommended Lists:
 11 
Benoit Mandelbrot
(American Mathematician and Polymath Best Known for Popularizing the Concept of Fractal Geometry)
Benoit Mandelbrot
24
Birthdate: November 20, 1924
Sun Sign: Scorpio
Birthplace: Warsaw, Poland
Died: October 14, 2010

Noted mathematician and polymath, Benoit B. Mandelbrot is perhaps best known for his work on fractal. He not only coined the term, but also used computer-constructed images to illustrate the mathematical definition. Also credited with the discovery of Mandelbrot set and Mandelbrot law, he established that even those things which were apparently chaotic or rough had a "degree of order".

 12 
Dennis Ritchie
(American Computer Scientist Known for Creating the C Programming Language)
Dennis Ritchie
13
Birthdate: September 9, 1941
Sun Sign: Virgo
Birthplace: Bronxville, New York, United States
Died: October 12, 2011

Computer scientist, Dennis MacAlistair Ritchie, worked at Bell Labs Computing Sciences Research Center for most of his career, co-developing the Unix operating system and B programming language with Kenneth Thompson, co-winning the 1983 A.M. Turing Award for it. Earlier, he had also created C programming language and was involved with the development of the Plan 9 and Inferno operating systems.

 13 
Katherine Johnson
(Mathematician and One of the First African-American Women to Work as a NASA Scientist)
Katherine Johnson
40
Birthdate: August 26, 1918
Sun Sign: Virgo
Birthplace: White Sulphur Springs, West Virginia, United States
Died: February 24, 2020
Katherine Johnson was a physicist and mathematician, remembered as the first African-American female NASA scientist. Her calculations helped launch the space missions of Alan Shepard and John Glenn. She was crucial to the Apollo program and won a Congressional Gold Medal and a Presidential Medal of Freedom for her achievements.
 14 
A.P.J. Abdul Kalam
(Aerospace Scientist & 11th President of India)
A.P.J. Abdul Kalam
16
Birthdate: October 15, 1931
Sun Sign: Libra
Birthplace: Rameswaram, Tamil Nadu, India
Died: July 27, 2015
A. P. J. Abdul Kalam, India’s 11th president, had earlier been an aerospace scientist at DRDO and ISRO. Known as the “People’s President” and the “Missile Man of India,” he was instrumental in India's Pokhran-II nuclear tests. He died of a cardiac arrest while delivering a lecture at IIM Shillong.
 15 
Peter Higgs
(British Theoretical Physicist and Nobel Prize Laureate for His Work on the Mass of Subatomic Particles)
Peter Higgs
7
Birthdate: May 29, 1929
Sun Sign: Gemini
Birthplace: Newcastle upon Tyne, England

Peter Higgs is a British theoretical physicist. He studied at King's College London and was awarded a Ph.D. in 1954. He went on to have a brilliant academic career and was elected Fellow of the Royal Society (FRS) in 1983. In 2013, he shared the Nobel Prize in Physics with Belgian physicist François Englert.  

 16 
Ken Thompson
(Computer Scientist)
Ken Thompson
17
Birthdate: February 4, 1943
Sun Sign: Aquarius
Birthplace: New Orleans, Louisiana, United States
Height: 6'8" (203 cm)
 17 
Marvin Minsky
(Mathematician, Computer scientist, University teacher)
Marvin Minsky
16
Birthdate: August 9, 1927
Sun Sign: Leo
Birthplace: New York City
Died: January 24, 2016
 18 
Tasuku Honjo
(Nobel Prize-Winning Japanese Immunologist Who Is Known for His Research on Cancer Immunotherapy)
Tasuku Honjo
18
Birthdate: January 27, 1942
Sun Sign: Aquarius
Birthplace: Kyoto, Kyoto Prefecture, Japan

Nobel Prize-winning Japanese immunologist Tasuku Honjo is known identifying the programmed cell death protein 1 and for revolutionizing cancer immunotherapy. Initially part of the University of Tokyo's faculty of medicine, he later taught genetics, immunology, and medical chemistry at several institutes. He was a foreign associate of the U.S. National Academy of Sciences.

 19 
Juliane Koepcke
(Lone Survivor of 1971 LANSA Plane Crash)
Juliane Koepcke
9
Birthdate: October 10, 1954
Sun Sign: Libra
Birthplace: Lima, Peru
Juliane Koepcke is a German Peruvian mammalogist. She is well-known for being the only survivor of the Líneas Aéreas Nacionales S.A. Flight 508 plane crash; she survived ten days in the Amazon rainforest after surviving a fall of 9843 feet while strapped to her airplane seat. Her story inspired films like Miracles Still Happen (1974) and Wings of Hope (1998).
 20 
Ahmed Zewail
(Chemist)
Ahmed Zewail
5
Birthdate: February 26, 1946
Sun Sign: Pisces
Birthplace: Damanhour, Egypt
Died: August 2, 2016
 21 
Bennet Omalu
(Forensic Pathologist Known for His Research in ‘Chronic Traumatic Encephalopathy’ in American Football Players)
Bennet Omalu
8
Birthdate: September 30, 1968
Sun Sign: Libra
Birthplace: Idemili South, Nigeria

Nigerian-American physician, forensic-pathologist and neuropathologist Bennet Omalu is most-noted for discovering chronic traumatic encephalopathy (CTE) in American football players. He was serving at Allegheny County coroner's office in Pittsburgh at that time. He presently serves as President and Medical Director of Bennet Omalu Pathology, chief medical examiner for San Joaquin County, and as professor at the University of California, Davis.

 22 
Vera Rubin
(American Astronomer Known for Her Pioneering Work on Galaxy Rotation Rates)
Vera Rubin
9
Birthdate: July 23, 1928
Sun Sign: Leo
Birthplace: Philadelphia, Pennsylvania, United States
Died: December 25, 2016

American astronomer Vera Rubin is best known for her pioneering discoveries on galaxy rotation rates, her groundbreaking work confirming the existence of dark matter and for her life-long advocacy for women in science. She studied the galactic rotation curves and provided strong evidence of the existence of dark matter. The Vera C. Rubin Observatory in Chile is named after her.

 23 
Michio Kaku
(Theoretical Physicist and Author of the Best-Selling Books ‘Physics of the Impossible’ and ‘Physics of the Future')
Michio Kaku
21
Birthdate: January 24, 1947
Sun Sign: Aquarius
Birthplace: San Jose, California, United States

Apart from teaching at the City College of New York, theoretical physicist Michio Kaku also often pens his thoughts in blogs and has written several bestselling books, such as The God Equation. His research is focused on the string theory. He also believes in the existence of aliens.

 24 
Dorothy Vaughan
(American Mathematician, Human Computer and the First African-American to Receive Promotion as Supervisor in NASA)
Dorothy Vaughan
30
Birthdate: September 20, 1910
Sun Sign: Virgo
Birthplace: Kansas City, Missouri, United States
Died: November 10, 2008

American mathematician Dorothy Vaughan was also known as a "human computer." Initially a math teacher, she became the first African-American supervisor of NACA, later part of NASA, at a time when racial segregation was rampant in the U.S. Her contribution to the early American space programs is invaluable.

 25 
Mary Jackson
(Mathematician)
Mary Jackson
12
Birthdate: April 9, 1921
Sun Sign: Aries
Birthplace: Hampton, Virginia, United States
Died: February 11, 2005

American mathematician and aerospace engineer Mary Jackson went down in history as the first African-American woman to work as a NASA engineer. Initially a math teacher, she later joined NACA under Dorothy Vaughan and contributed to countless American space programs at a time when racial segregation was the norm.

 26 
Roger Penrose
(English Mathematician, Mathematical Physicist and Winner of the 2020 Nobel Prize for Physics)
Roger Penrose
16
Birthdate: August 8, 1931
Sun Sign: Leo
Birthplace: Colchester, England

Roger Penrose’s contribution to the research related to the black hole and general relativity earned him the Nobel Prize in Physics in 2020. The Emeritus Rouse Ball Professor of Mathematics at Oxford, Roger is also a fellow of Wadham College, St John's College of Cambridge, and University College London.

 27 
James Watson
(Molecular Biologist Who Co-discovered the Double Helix Structure of DNA With Francis Crick)
James Watson
13
Birthdate: April 6, 1928
Sun Sign: Aries
Birthplace: Chicago, Illinois, United States

James Watson is a geneticist, molecular biologist, and zoologist. He is credited with co-authoring the academic paper that propounded the double helix structure of nucleic acids such as DNA for which he was awarded the Nobel Prize in 1962. In 1977, he was honored with the Presidential Medal of Freedom. In 1997, he was awarded the National Medal of Science.

 28 
Sir Arthur Charles Clarke
(Science-Fiction Writer Known for His Novels: ‘Childhood's End’, ‘2001: A Space Odyssey’ and ‘Rendezvous with Rama’)
Sir Arthur Charles Clarke
8
Birthdate: December 16, 1917
Sun Sign: Sagittarius
Birthplace: Minehead, Somerset, England
Died: March 19, 2008
Sir Arthur C. Clarke is best known for his short story The Sentinel, which became the basis of the screenplay of Stanley Kubrick’s science-fiction movie 2001: A Space Odyssey. Clarke spent the final years of his life in Sri Lanka and hosted shows such as Arthur C. Clarke's Mysterious World.
 29 
Temple Grandin
(Scientist)
Temple Grandin
7
Birthdate: August 29, 1947
Sun Sign: Virgo
Birthplace: Boston, Massachusetts, United States

Temple Grandin is an American activist and scientist. An outspoken proponent of the neurodiversity and autism rights movements, Grandin is one of the first individuals to document the insights gained from her own experience of autism. She has also authored over 60 scientific papers on animal behavior. Her life and work inspired the 2010 biographical drama film Temple Grandin.

 30 
Norman Borlaug
(American Agronomist and Winner of the Nobel Prize for Peace in 1970)
Norman Borlaug
6
Birthdate: March 25, 1914
Sun Sign: Aries
Birthplace: Cresco, Iowa, United States
Died: September 12, 2009

Norman Borlaug was an American agronomist who played a key role in the Green Revolution, a set of research technology transfer initiatives that increased agricultural production, for which he won the Nobel Peace Prize in 1970. Nicknamed the Father of the Green Revolution, Borlaug was also honored with the Congressional Gold Medal and Presidential Medal of Freedom for his work.

 31 
Alan Kay
(Computer Scientist)
Alan Kay
8
Birthdate: May 17, 1940
Sun Sign: Taurus
Birthplace: Springfield, Massachusetts
 32 
Luc Montagnier
(French Virologist & Discoverer of HIV)
Luc Montagnier
8
Birthdate: August 18, 1932
Sun Sign: Leo
Birthplace: Chabris, France
Died: February 8, 2022

French virologist Luc Montagnier is known for discovering the human immunodeficiency virus (HIV) which led him to jointly receive the 2008 Nobel Prize in Physiology or Medicine. Montagnier also made headlines promoting controversial and unverified claims related to vaccinations, homeopathy and COVID-19 pandemic, which he argued as man-made and possibly a result of an attempt to create an HIV/AIDS vaccine.

 33 
Mario J. Molina
(Mexican Chemist Who Won Nobel Prize for Discovering the Threat to Earth's Ozone Layer from CFC Gases)
Mario J. Molina
4
Birthdate: March 19, 1943
Sun Sign: Pisces
Birthplace: Mexico City, Mexico
Died: October 7, 2020

Mario J. Molina was a Mexican chemist who played a key role in understanding and explaining the threat from chlorofluorocarbon (CFC) gases to the Earth's ozone layer, which earned him the prestigious Nobel Prize in Chemistry in 1995. Molina was the third Mexican-born Nobel laureate and the first Mexican-born person to win a Nobel Prize in Chemistry.

 34 
James Gosling
(Programmer, Inventor, Computer scientist)
James Gosling
13
Birthdate: May 19, 1955
Sun Sign: Taurus
Birthplace: Calgary

James Gosling earned the nickname Dr. Java after he revolutionized the world of computer programming with his Java programming language. The Carnegie Mellon alumnus has had a 26-year stint with Sun Microsystems. The computer nerd has a picture of the first 1000 digits of √2 framed in his office.

 35 
Hilary Putnam
(Mathematician, Philosopher)
Hilary Putnam
5
Birthdate: July 31, 1926
Sun Sign: Leo
Birthplace: Chicago, Illinois, United States
Died: March 13, 2016
 36 
Andrew Wiles
(English Mathematician)
Andrew Wiles
22
Birthdate: April 11, 1953
Sun Sign: Aries
Birthplace: Cambridge, United Kingdom

English mathematician Sir Andrew John Wiles, a Royal Society Research Professor at the University of Oxford, is best known for proving the modularity theorem for semistable elliptic curves, thereby proving Fermat's Last Theorem for which he was awarded the Abel Prize and the Copley Medal by the Royal Society. He also proved the main conjecture of Iwasawa theory.

 37 
Kip Thorne
(Physicist)
Kip Thorne
5
Birthdate: June 1, 1940
Sun Sign: Gemini
Birthplace: Logan

American theoretical-physicist Kip Thorne, who is noted for his contributions in gravitational physics and astrophysics, is known for Thorne-Żytkow object, Thorne-Hawking-Preskill bet, LIGO, gravitational waves and the book Gravitation. Thorne along with Rainer Weiss and Barry C. Barish received the Nobel Prize in Physics in 2017 for their contributions to the LIGO detector and the observation of gravitational waves.

 38 
Jennifer Doudna
(American Biochemist Known for the Invention of 'CRISPR Gene Editing')
Jennifer Doudna
5
Birthdate: February 19, 1964
Sun Sign: Pisces
Birthplace: Washington, D.C., United States

American biochemist Jennifer Doudna of the University of California, Berkeley, who has made fundamental contributions in biochemistry and genetics, is best-known for her pioneering work in CRISPR gene-editing. Doudna and Emmanuelle Charpentier received the 2020 Nobel Prize in Chemistry for developing a method for genome editing through CRISPR, marking them as the only two women to share science Nobel ever.

 39 
David Suzuki
(Canadian Academic, Environmental Activist and Host of TV Program ‘The Nature of Things’)
David Suzuki
7
Birthdate: March 24, 1936
Sun Sign: Aries
Birthplace: Vancouver, Canada
Best known for the CBC show The Nature of Things, Canadian environmental activist David Suzuki has also been a genetics and zoology professor. The UN Environment Programme Medal winner has been a major force against global warming and has written several books, such as An Introduction to Genetic Analysis.
 40 
James Harris Simons
(Mathematicians & Hedge Fund Manager)
James Harris Simons
10
Birthdate: April 25, 1938
Sun Sign: Taurus
Birthplace: Newton

The son of a shoe factory owner, mathematician-turned-hedge-fund-manager James Harris Simons studied math at MIT and helped the U.S. break codes during the Vietnam War. He later founded his own hedge fund firm, Renaissance Technologies. He supports autism research and funds Math for America. In 2021, he was America’s 23rd-richest person.

 41 
Tony Hoare
(Computer scientist)
Tony Hoare
6
Birthdate: January 11, 1934
Sun Sign: Capricorn
Birthplace: Colombo, Sri Lanka

Tony Hoare is a British computer scientist who is credited with developing the sorting algorithm quicksort. He is also credited with developing Hoare logic, a formal system for verifying program correctness. Over the years, Tony Hoare has received several prestigious awards for his contribution to computer science.

 42 
Freeman Dyson
(Mathematician)
Freeman Dyson
9
Birthdate: December 15, 1923
Sun Sign: Sagittarius
Birthplace: Crowthorne, England
Died: February 28, 2020

Freeman Dyson was a British-American theoretical and mathematical physicist, mathematician, and statistician. He made major contributions in the fields of quantum field theory, astrophysics, random matrices, quantum mechanics, and nuclear physics. He originated the concept that went on to be known as Dyson's transform. He received the Golden Plate Award of the American Academy of Achievement in 1986. 

 43 
Murray Gell-Mann
(Physicist)
Murray Gell-Mann
7
Birthdate: September 15, 1929
Sun Sign: Virgo
Birthplace: Manhattan, New York City, U.S.
Died: May 24, 2019

Nobel Prize-winning American physicist Murray Gell-Mann is best remembered for his research on elementary particles. The Yale and MIT alumnus later taught at Caltech and is credited with coining the terms "quark" and "strangeness" in quantum physics. A linguistic enthusiast, he also co-established the Evolution of Human Languages program.

 44 
Walter Lewin
(Astronomer, University teacher, Astrophysicist, Physicist)
Walter Lewin
13
Birthdate: January 29, 1936
Sun Sign: Aquarius
Birthplace: The Hague
 45 
Jared Diamond
(American Historian, Geographer, Author, and Ornithologist)
Jared Diamond
9
Birthdate: September 10, 1937
Sun Sign: Virgo
Birthplace: Boston, Massachusetts, United States

Jared Diamond is an American historian, geographer, author, and ornithologist. He is best known for his books, The Third Chimpanzee, Collapse, Upheaval, and The World Until Yesterday. His 1997 book Guns, Germs, and Steel earned him the prestigious Pulitzer Prize. In 1999, he was awarded the National Medal of Science. Jared Diamond is currently working as a professor at UCLA.

 46 
Andre Geim
(Dutch-British Physicist Known for His Discovery of 'Graphene')
Andre Geim
4
Birthdate: October 21, 1958
Sun Sign: Libra
Birthplace: Sochi, Russia

Andre Geim is a Russian-born Dutch-British physicist. He has been associated with the School of Physics and Astronomy at the University of Manchester for several years. In 2010, he was awarded the Nobel Prize in Physics jointly with Konstantin Novoselov in recognition of his work on graphene. He is also a recipient of the 2000 Ig Nobel Prize in Physics. 

 47 
Jim Cantore
(American Meteorologist Best Known as an On-Air Personality for 'The Weather Channel')
Jim Cantore
8
Birthdate: February 16, 1964
Sun Sign: Aquarius
Birthplace: Beacon Falls, Connecticut, United States
Best known for his long stint on The Weather Channel, meteorologist Jim Cantore has gained fame for making his weather reports interesting to even a lay person. He has hosted weather segments for the 2012 Summer Olympics and is also known for his authentic storm reports, which have often become viral.
 48 
Harrison Schmitt
(American Astronaut and the Only Person Without a Background in Military Aviation to Have Walked on the Moon)
Harrison Schmitt
4
Birthdate: July 3, 1935
Sun Sign: Cancer
Birthplace: Santa Rita, New Mexico, United States

Harrison Schmitt is an American geologist, university professor, and former NASA astronaut. He also served as the US Senator from New Mexico from 1977 to 1983. In 1972, Schmitt became a crew member of Apollo 17 and subsequenly the second-youngest person to walk on the Moon. In 1973, Harrison Schmitt was honored with the NASA Distinguished Service Medal.

 49 
Peggy Whitson
(Biochemistry Researcher and First Female Astronaut to Command the International Space Station)
Peggy Whitson
7
Birthdate: February 9, 1960
Sun Sign: Aquarius
Birthplace: Beaconsfield, Iowa, United States

The first woman to command the International Space Station, NASA astronaut Peggy Whitson was born to farmers and decided to become an astronaut after watching the moon landing on TV. She also boasts of a PhD in biochemistry and has been a researcher and educator of biochemistry and genetic engineering.

 50 
Brian Greene
(American Theoretical Physicist and Mathematician)
Brian Greene
6
Birthdate: February 9, 1963
Sun Sign: Aquarius
Birthplace: New York, New York, United States

American theoretical physicist, mathematician, and string theorist Brian Greene is noted for popularising string theory through his books like The Elegant Universe, and The Fabric of the Cosmos and related PBS television specials. Greene taught as professor of physics at Cornell University, and presently serves as a professor at Columbia University. He is the co-founder and chairman of the World Science Festival.