[3] Companies started via Y Combinator include Airbnb, Coinbase, Cruise, DoorDash, Dropbox, Instacart, Reddit, Stripe, and Twitch.

[4] Founded in 2005 by Paul Graham, Jessica Livingston, Robert Tappan Morris, and Trevor Blackwell,[5] Y Combinator (YC) initiated operations with concurrent programs in Cambridge, Massachusetts, and Mountain View, California.

[6] Although often overlooked in early accounts, Jessica Livingston played a pivotal role in shaping Y Combinator's culture and success.

[7] In 2009, Y Combinator secured a $2 million investment led by Sequoia Capital, enabling increased annual funding for around 60 companies.

[8] Sequoia further supported YC in 2010 through an $8.25 million funding round, bolstering the organization's capability to accommodate a growing number of startups.

[9] Concurrently, Kirsty Nathoo joined the team, initially as an accountant, and subsequently as the Chief Financial Officer (CFO) in 2012.

[15] In September 2013, Y Combinator began funding nonprofit organizations that were accepted into the program after testing the concept with Watsi.

[20][21][non-primary source needed] Global outreach became evident in 2016 as YC partners embarked on visits to 11 countries (Nigeria, Denmark, Portugal, Sweden, Germany, Russia, Argentina, Chile, Mexico, Israel, and India) to engage with founders and learn about international startup communities.

[33] In January 2022, a revised standard deal of $500,000 was introduced, comprising $125,000 for a 7% equity stake and an additional $375,000 via an uncapped safe mechanism incorporating a Most Favored Nation (MFN) clause.

Founders also participate in weekly meetups where guests from the Silicon Valley ecosystem (successful entrepreneurs, venture capitalists, etc.)

The program ends with "Demo Day", where startups present their business and technology prototypes to potential investors.

[54] Few non-profits have been accepted in the last years, among them Watsi, Women Who Code, New Story, SIRUM, Zidisha, 80,000 Hours, and Our World in Data.

Members included Alan Kay, Dan Ingalls, Bret Victor, Vi Hart, and Patrick Scaglia.