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.

Startups are small, early-stage companies designed to grow fast

The definition of the word “startup” is complicated—so who better to define it than Y Combinator, perhaps the most well-known startup accelerator in the business? YC’s blog also explains how startups make money and build products.

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.

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.

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

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.

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.

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.

Coined in 1971, the man credited with naming Silicon Valley was originally writing about semiconductors

Silicon Valley gained its name from an article published in January 1971, in Electronic News. Author Don Hoefler used the term in his headline for an article he was writing about the semiconductor industry. Hoefler is credited with naming the multi-trillion dollar area that is still called Silicon Valley today.

ChatGPT was conceived over dinner at a Silicon Valley hotel

A guest list of tech leaders, including Elon Musk, Peter Thiel, and LinkedIn cofounder Reid Hoffman, met to discuss how to counter Google's efforts to create human-level cognition systems. The group initially committed a reported $1B to launch the effort.

Google's early focus on simplicity and user experience drove its future successes

Google Search revolutionized information retrieval in 1998, but additional web-based products, including Gmail, Maps, Docs, and YouTube reinforced the company's core ad business while allowing it to aggregate the world's information. Forming Alphabet protected this business from riskier moonshot projects.

The early success of Facebook made Mark Zuckerberg a college campus celebrity

Within 24 hours of launching in 2004, more than 1,200 Harvard students signed up to the platform, which quickly expanded to other Ivy League and Boston-area schools within months. By year's end, Zuckerberg left Harvard to run the company in California.

The first computer virus was created by a USC doctoral candidate in 1983

A year after creating malware in a controlled experiment that multiplied until it took over all of a computer's memory, Fred Cohen went public with his research and its risks. He called the self-replicating software a "computer virus," a term Cohen's advisor, Leonard Adleman, coined to describe its infectious behavior. (Some readers may experience a paywall.)

The first compiler to facilitate communication with computers was developed by Grace Hopper

The A-0 program linker automatically translated mathematical symbols into machine-readable binary code. Although it took two years for computer executives to get on board with the idea, the technology was foundational to future programming languages that allowed computers to understand commands written in word-based languages.

Bill Gates and Paul Allen were childhood friends before founding Microsoft

The two bonded over a teletype terminal at their school, which required a $40 hourly fee for computing time. They were banned from using the device after exploiting a bug that allowed them to bypass the fee, only to be later offered free computing time for finding more bugs.

Bumble was originally created under the MagicLab parent company

When Blackstone acquired MagicLab in 2019, Bumble Founder and CEO Whitney Wolfe Herd was elevated to CEO of the entire parent company (which also owned Indian dating app Badoo). The parent company was rebranded as Bumble Inc.

Apple's first backer recruited his own CEO to help manage the company

Wanting Steve Jobs and Steve Wozniak to focus on developing Apple computers, Mike Markkula brought in his colleague from Fairchild Semiconductor, Michael Scott. As employee number five, Scott helped professionalize the fledgling computer company and getting manufacturing off the ground. (Some users may experience a paywall.)

Youtube, explained

YouTube began as a quirky site where users uploaded funny, random videos—a do-it-yourself television service. Today, it’s a global media powerhouse and home to everything from movie trailers to video podcasts, livestreams, and much more. Want to learn more about the streaming giant? Check out our 5-minute explainer here.

Sears once tried to become a tech company

In 1984, Sears arguably created one of the first online retail services, called “Prodigy,” in 1984 alongside IBM and CBS. But it was more of a WeChat than an Amazon, offering a variety of other services to users a few years before the dot com era.

WeWork’s competitors in the coworking space include Industrious and The Malin

WeWork’s story is colored by the times it just couldn’t make its numbers work. Its competitors in the coworking industry, such as Industrious and Convene, seem to be prioritizing slow and stable financial growth instead.

Computer scientists first started trying to optimize dating using computers in the 1950s

Although early dating sites like Match.com weren't launched until the 1990s, the history of dating apps dates arguably back to the mid-1900s when computer scientists used IBM computers to solve matchmaking and compatibility problems.

Jim Simons, mathematician turned government codebreaker turned trader, revolutionized quantitative investing

The late Jim Simons is remembered as one of the most successful (and profitable) hedge fund managers of all time. He went from physically gathering microfilm on commodities pricing decades ago to overseeing a firm that led Wall Street in daily trading volume.

Amazon operates a 'flywheel' business model

Central to any understanding of the multifaceted nature of Amazon's business today is the concept of the "flywheel" at the heart of the company. Put simply, it's an idea that refers to a self-reinforcing cycle that drives the continuous growth of Amazon's various businesses, including its retail arm, its Prime subscription service, and more.

In 2017, Yale renamed one of its colleges to honor Grace Hopper

Founded in 1933, the Calhoun College—one of Yale's 12 undergraduate residential colleges—was renamed to Grace Hopper College in honor of the woman who earned a master's degree and PhD in mathematics from the university in the 1930s. The change was also made to distance the school from white supremacist John C. Calhoun.

Learn more about Palantir's 'meritocracy fellowship'

In 2025, Palantir launched a fellowship program for high school graduates to bypass college and begin working at Palantir. The fellowship is positioned as an alternative to American universities, which Palantir leaders and cofounders frequently criticize, and offers students four months of paid training, seminars from business leaders, and return offers to top students.

X (Twitter) started as a way to share short updates via text

What began as a way to share 140-character updates quickly grew into a vital platform for activism, politics, and pop culture. Hashtags, trending topics, and retweets—now common across the internet—originated on the platform.

The software for wikis—user-editable websites—was launched in 1995

Computer programmer Ward Cunningham created the WikiWikiWeb online application based on an offline system that helped track how ideas moved through his company. The application enabled users to collaborate and edit website content through a web browser, as well as link pages without requiring a structured navigation scheme.

The Grateful Dead's online bulletin board system inspired the early internet

The legendary countercultural band the Grateful Dead had a popular hub on The Well, an online extension of the Whole Earth Catalog, a popular hippie magazine in the '60s and '70s. Users included Craig Newmark (founder of Craigslist), Steve Case (founder of AOL), and Steve Wozniak (cofounder of Apple).

A list of MBA jargon, complete with a ‘corporate BS generator’

From the classroom to the boardroom, MBA students hear plenty of corporate jargon in their lifetimes (think: “bandwidth,” “turnkey solution,” “modularize,” and more). This website—a relic from the internet—includes an MBA jargon dictionary and a corporate BS generator tool that creates helpful phrases for office life, like “incubate synergistic e-markets.”

Computational and biological systems share fundamental principles, like randomness

Proposed by Alan Turing and John von Neumann, the concept originates from how DNA and computers run by executing encoded instructions in parallel. The advent of AI and the temperature parameter has seen neural networks mimic the randomness of protein encoding.