Y Combinator, the startup accelerator, gets its name from the 'Y combinator' computer science concept.

Y Combinator was founded in 2005 to bridge gaps between founders and investors

In one of Paul Graham’s essays on his website, he took the time to explain how and why he and his cofounders (including his girlfriend at the time, and now wife, Jessica Livingston), came up with the idea of and eventually created Y Combinator.

YC was partly inspired by an investor named Julian Weber

Y Combinator Cofounder Paul Graham’s former professor’s husband Julian Weber provided $10K in seed funding to Graham’s previous startup, Viaweb in its early days. In exchange, Weber received 10% of the company. Weber’s involvement inspired Graham to start a program where investors were more involved with the companies they contributed seed funding to.

Read Paul Graham’s initial post announcing YC’s first batch

In March 2005, Y Combinator cofounder Paul Graham announced the program that would become Y Combinator on his website.

Y Combinator changed the way startups around the world are built

Many of the philosophies that the leaders of Y Combinator have infused into the program’s portfolio companies have become the playbook for building the next big thing, such as its focus on founder personality and more.

Y Combinator cofounder, Jessica Livingston, once interviewed her husband and cofounder, Paul Graham

Two of Y Combinator's cofounders, Jessica Livingston and Paul Graham, were in a romantic relationship before they started the accelerator. They later married, and much later, Livingston started a podcast. In an episode of her podcast, Livingston and her cohost interview Graham about the beginning of YC and more.

The Y Combinator startup directory includes every company YC has funded

The startup accelerator has funded more than 5,000 companies over the years. This YC-specific search engine lets you look up any company to find out if it's a YC alum.

Y Combinator cofounder Paul Graham keeps a public archive of his insightful essays

In addition to cofounding Y Combinator and other companies before it, Paul Graham is a prolific writer and artist. He chronicled many of his thoughts while building Y Combinator in a series of dozens of candid essays, all of which you can read in an online archive.

Yahoo acquired Paul Graham's former startup Viaweb in 1998

Viaweb was the web app tech startup that Paul Graham, Robert Morris, and Trevor Blackwell cofounded before they started Y Combinator. The company sold for $49M and Viaweb was rebranded as the Yahoo Store.

Visualize where the first batch of founders from the famous startup accelerator Y Combinator are now.

Startup accelerators that include more training activities, such as pitch competitions, tend to have better long-term success rates

That's according to a new study from Wharton. Y-Combinator, perhaps the most famous startup accelerator, currently has 16 alumni companies trading on the public market. But not every entrepreneur who joins a startup accelerator makes it big.

Listen to a podcast episode where Y Combinator CEO Gary Tan explains why YC tends to outperform many other Silicon Valley startup accelerators.

Startup accelerators offer mentorship and seed funding in exchange for equity

Those programs, such as Y Combinator and Techstars, not only offer expert advice to founders, but also seed funding in exchange for equity. The goal is to help young startups learn from successful companies, making it more likely they attract venture capital.

CEO Gary Tan explains Y Combinators guiding philosophy

Hear YC President and CEO Garry Tan talk about why he values earnesty and excellent communication skills in YC founders, his thoughts on AI, and more in this unexpectedly deep and in-depth interview.

Stanford’s ‘How to Start a Startup’ series

Stanford’s archive of lectures about creating a startup includes advice from Y Combinator notables such as former YC president and OpenAI CEO Sam Altman and YC Cofounder Paul Graham.

87% of the startups in Y Combinator’s Fall 2025 batch were AI companies

Y Combinator also recently increased its number of cohorts or “batches” per year from two to four. Its leaders cited artificial intelligence’s rise as a reason for the increase.

For Reddit's founders, the company's early days included choosing a dinner with Y Combinator's Paul Graham over a spring break trip, a $10M Condé Nast acquisition, and other pivotal moments.

Y Combinator has a roughly 1% acceptance rate

That’s lower than the most elite universities and colleges in the world—but insiders have some tips about how applicants can have the best shot of being accepted to the selective startup accelerator.

'Founder mode' is the idea that startup founders should take a hands-on approach to running their businesses

In 2024, Y Combinator cofounder Paul Graham popularized the idea of "founder mode" when he wrote a viral manifesto in response to a talk that Airbnb CEO Brian Chesky gave about leadership styles. Graham positioned the concept of founder mode as the opposite of manager mode—when founders hire executives and middle managers to run their companies and make decisions that Graham says are better left to founders.

'Founder mode' is the idea that founders should take a hands-on approach to running their businesses

In 2024, Y Combinator Cofounder Paul Graham wrote a viral manifesto of sorts about a strategy he calls "founder mode." It's the opposite of what Graham calls "manager mode," which allows founders to hire executives who he says ultimately run the company into the ground.

Dive deep into the numbers that shape each YC deal

Y Combinator invests $500K into each company in any given batch. $125K of that investment converts into a fixed 7% in ownership of the startup, and the other $375K is invested on something called an uncapped MFN safe. YC explains what that means and more terms of the deal in a detailed article on their website

The term 'startup'—which is typically used to describe private companies in their early stages of operation that focus on innovating new products or services to meet a market gap—can be traced back to a 1976 Forbes article.

Explore the schedule of a three-month YC batch

During the three months that founders accepted into Y Combinator spend on YC’s California campus, they receive mentorship from YC partners, networking opportunities, and, overall, a ton of time to build and scale their companies.

Startups follow a 'minimum viable product' strategy to determine demand

Michael Seibel, group partner for startup incubator Y Combinator, explains how to build a minimum viable product (also known as an MVP) for any startup idea. Using real companies that experienced the Y Combinator program as examples, he walks through how to determine an MVP feature set, how to present an MVP to potential investors, and more.

Watch the DoorDash team's YC application video

In 2013, the cofounders of DoorDash created a simple, homemade video application to Y Combinator. They didn't know it at the time, but they'd be accepted—and their company would go on to be publicly traded on the NASDAQ.

Peter Thiel and Elon Musk formed PayPal after merging two dot-com companies

Elon Musk cofounded "X.com," an online banking service, in 1999 with the idea that the web would become a financial repository as internet access expanded and became ingrained in daily life. Peter Thiel cofounded "Confinity" as a digital security service that morphed into a payments system. In 2000, the two merged to form PayPal, and in 2002, they sold PayPal to eBay for $1.5B.

Mark Zuckerberg credits some of Facebook's success to constant evolution

Before becoming the head of OpenAI, Sam Altman was the president of Y Combinator—a startup accelerator company that supported companies like Airbnb, DoorDash, and Coinbase. In 2016, Altman interviewed Zuckerberg about creating Facebook and its growth over time. Zuckerberg said that, unlike other companies (think: CourseMatch), Facebook kept growing and adding new features, which prevented the app from becoming obsolete.

How venture capital firms came to be

The venture capital firm that kickstarted an industry.

The dot-com bubble burst in the early 2000s

If you’ve heard of companies like Google and Yahoo, you’re already partially familiar with the dot-com bubble: a period from roughly 1995 to 2001, when internet companies were the hottest thing in venture capital. The “bubble” part of the term refers to the industry’s eventual implosion.

‘Demo days’ are when founders at Y Combinator pitch their startup ideas

Investors sit in the audience, waiting to hear what this season’s batch of YC founders have cooked up. YC argues that going through the process of a demo day can help founders get a better understanding of their startup themselves.

Legendary venture capitalist Peter Thiel once wrote that 'competition is for losers'

With Peter Thiel's "Monopoly Theory," the Founders Fund partner argued that investing in companies that create new categories, rather than those that compete with other businesses in existing ones, is a best practice in venture capital.

Venture capital is a type of financing that firms and funds use to invest in startups they believe have the potential for long-term growth

Household name companies such as Airbnb and Uber might not exist without venture capital, which is commonly referred to as "VC" for short.

Andreessen Horowitz is among the most well-known venture capital firms

Also known as a16z, the firm has invested in companies such as Airbnb, Facebook, and Lyft since its founding in 2009. A podcast episode offers a deep dive into how the firm got started and became the industry disruptor it is today.

Many startup founders pull out-of-the-box stunts to get their businesses off the ground.

YouTube began as a quirky site invented by former PayPal employees

In February 2005, YouTube was launched by Steve Chen, Chad Hurley, and Jawed Karim. Their idea was to build a platform to support the convenient sharing of videos online, a relatively novel idea in the days of cable TV and early social media.

Bill Hewlett and Dave Packard are known for creating the 'founding' Silicon Valley company Hewlett-Packard

During the company's early years, Hewlett and Packard established a management approach called "the HP Way." The approach, which was considered radical at the time, helped shape the way Silicon Valley is run today.

Nonprofit VC funds invest in startups, but have donors instead of LPs

Examples include Andreessen Horowitz’s TxO (Talent x Opportunity) Initiative and Fifth Star Funds, which allows donors to write “Friends & Family” checks for Black tech founders.

ChatGPT was conceived over dinner at a Silicon Valley hotel.