Y Combinator is a prominent startup accelerator that provides seed funding, mentorship, and resources to early-stage companies. Founded in 2005, it has supported over 5,000 startups, including Airbnb, Dropbox, and Stripe. Y Combinator invests in selected companies through its batch program, offering guidance from experienced partners and access to a vast network of alumni and investors. The firm focuses on helping founders build scalable businesses across various sectors, including technology, healthcare, and consumer services.