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.

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 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.

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.

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.

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

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 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.

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.

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.

Sam Altman gave his first-ever startup pitch after dropping out of Stanford

He dropped out of Stanford to start Loopt, which sold in 2012 for $43.4M. You can watch his first-ever startup pitch in a video.

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.

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.

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.

Stanford and Harvard are among the universities producing the most startup founders

Not all startup founders are created equal. This data visualization of the universities that produce the most startup founders is based on the number of alumni who have raised venture capital funding for their companies. That means these alums had to do much more than put "entrepreneur" in their LinkedIn bio to be considered startup founders.

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.

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.

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.

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.

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.

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.

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

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

How venture capital firms came to be

The venture capital firm that kickstarted an industry.

‘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.

Three AI startup founders broke the record for the youngest self-made billionaire previously set by Mark Zuckerberg

Mark Zuckerberg became the youngest self-made billionaire in 2006 at 23 years old when Facebook held its initial public offering. In January of 2026, three AI startup founders—Brendan Foody, Adarsh Hiremath, and Surya Midha—broke Zuckerberg's record and became billionaires at 22 years old.

7 angel investors funded Google in its early days

Entrepreneur Shaan Puri shares how seven strangers acted as Google’s earliest angel investors. The first gave Google $100K without even putting his equity agreement in writing. The investors on “Shark Tank” use their personal funds to support startups, but they’re often more predatory about terms than typical angels.

OpenAI helped kick-start an AI arms race in Silicon Valley

Led by CEO Sam Altman, OpenAI's mission is to "ensure artificial general intelligence benefits all of humanity" by making its products open to all users. In 2023, the $86B company behind the chatbot ChatGPT consisted of a for-profit arm under its nonprofit governing board.

From 19th-century whalers to startup accelerators, venture capital has a pretty exciting history

While the aforementioned whaling industry has a lot of similarities to today’s venture fund models, the first modern venture capital firm wasn’t founded until 1946.

See a list of 2024’s top 10 VC firms

A list of the top 10 VC firms, like Sequoia Capital and Andreessen Horowitz, ranked by assets under management shows how those two firms stack up against their competitors—and what kinds of companies those competitors invest in.

Learn how eight 'traitors' played an essential role in founding Silicon Valley

In the 1950s, William Shockley led the way in the semiconductor business. Everything changed in 1957, after eight of his engineers—whom he called the "Traitorous Eight"—left his company to start their own. Their company, named Fairchild Semiconductor, employed many future founders of major Silicon Valley companies. Today, the Traitorous Eight are considered among the founders of Silicon Valley.

'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.

See a web of circular investments among major AI industry players like Nvidia and OpenAI, as many top AI companies provide significant investments to one another.

Many of the 2010s girlboss-era founders experienced a public fall from grace in 2020

In the 2010s, dozens of female founders were celebrated on the covers of business magazines like Inc. for their recent startup success, from Emily Weiss’s Glossier makeup brand to Steph Korey’s Away luggage company. But many of these companies were also the subject of large takedown articles around the year 2020.