Purdue University is the largest university in Indiana in terms of student enrollment and is located in West Lafayette. It was founded in 1869 It is probably the greatest rival to Indiana University. The two universities have joined together for the IUPUI campus in Indianapolis and the IPFW campus in Fort Wayne. The IUPUI campus is administered by Indiana University while the IPFW campus is administered by Purdue University.
Purdue University's abbreviation is usually just PU, but a lot of times you will hear the phrase IU and Purdue or IU vs. Purdue.