Y Combinator, the startup accelerator, was founded in 2005.
Paul Graham, Jessica Livingston, Robert Tappan Morris, and Trevor Blackwell established Y Combinator in Cambridge, Massachusetts. Its first funding cycle began that year, making it an early model for the modern technology accelerator.
Y Combinator provides seed funding, advice, and a structured program that culminates in a public Demo Day. It later moved its operations to Silicon Valley and became associated with companies including Airbnb, Dropbox, Reddit, and Stripe.
The accelerator is often confused with a venture-capital fund. Its defining feature is a fixed program for groups of early-stage startups, rather than only individually negotiated investments. Y Combinator helped popularize the batch-based accelerator format now common in startup culture.