Purdue University is a public land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donated land and money to establish a college of science, technology, and agriculture; the first classes were held on September 16, 1874.

Purdue University is a member of the Association of American Universities and is classified among "R1: Doctoral Universities – Very high research activity". Purdue enrolls the largest student body of any individual university campus in Indiana, as well as the ninth-largest foreign student population of any university in the United States. The university is home to the oldest computer science program and the first university-owned airport in the United States.

Purdue is the founding member of the Big Ten Conference and sponsors 18 intercollegiate sports teams. It has been affiliated with 13 Nobel laureates, 1 Turing Award laureate, 1 Bharat Ratna recipient, 27 astronauts, 2 World Food Prize laureates, 3 Pulitzer Prize winners, 18 Olympic medalists, 3 National Medal of Technology and Innovation recipients, 2 National Medal of Science recipients, 3 Presidential Medal of Freedom recipients, 7 members of Congress, 3 U.S. governors, and 2 heads of state.

In 1865, the Indiana General Assembly voted to take advantage of the Morrill Land-Grant Colleges Act of 1862 and began plans to establish an institution with a focus on agriculture and engineering with the preliminary name of the Indiana Agricultural College. Communities throughout the state offered facilities and funding in bids for the location of the new college. Popular proposals included designating Indiana University or what is now Butler University as Indiana's land-grant, as well as the addition of an agriculture department at what is now Indiana State University. By 1869, Tippecanoe County's offer included $150,000 (equivalent to $3.5 million in 2024) from Lafayette business leader and philanthropist John Purdue; $50,000 from the county; and 100 acres (0.4 km²) of land from John Purdue and local residents.

On May 6, 1869, the General Assembly established the institution in Tippecanoe County as Purdue University, in the name of the principal benefactor. Classes began at Purdue on September 16, 1874, with six instructors and 39 students. Professor John S. Hougham was Purdue's first faculty member and served as acting president between the administrations of presidents Shortridge and White. A campus of five buildings was completed by the end of 1874. In 1875, Sarah D. Allen Oren Haynes, the State Librarian of Indiana, was appointed professor of botany.

Purdue issued its first degree, a Bachelor of Science in chemistry, in 1875. The first female student was admitted that autumn.

Emerson E. White, the university's president from 1876 to 1883, followed a strict interpretation of the Morrill Act. Rather than emulate the classical universities, White believed Purdue should be an "industrial college" and devote its resources toward providing a broad, liberal education with an emphasis on science, technology, and agriculture.

Part of White's plan to distinguish Purdue from classical universities included a controversial attempt to ban fraternities, which was ultimately overturned by the Indiana Supreme Court. White resigned in protest. The next president, James H. Smart, is remembered for his call in 1894 to rebuild the original Heavilon Hall "one brick higher" after it had been destroyed by a fire.