Y Combinator (YC) is a renowned American seed money startup accelerator founded in March 2005 by Paul Graham, Jessica Livingston, Trevor Blackwell, and Robert Tappan Morris. It has played a pivotal role in the launch of over 2,000 companies, including high-profile successes such as Dropbox, Airbnb, and Stripe. Y Combinator's business model is centered around providing seed funding, advice, and connections to early-stage startups in exchange for equity. Twice a year, it selects a batch of startups to participate in a three-month program that culminates in a Demo Day, where entrepreneurs present their business to a carefully selected, invite-only audience. YC's approach is highly influential in the startup ecosystem, setting trends in investment and startup development strategies.