Y Combinator changed the way startups around the world are built

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.

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.

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.

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.

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

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.

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.

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.

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 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.

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.

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.

'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.

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.

'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

‘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.

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.

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

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, 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.

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.

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.

Airbnb's Brian Chesky explains 'Founder Mode' and how he took back control

The short-term rental CEO learned hard lessons through the pandemic, specifically around a culture focused on management and not building products. In the fall of 2024, Chesky gave a well-received speech at a startup conference that prompted debate in the startup world. He summarizes the talk here.

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.

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.

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.

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.

Working at a startup isn't for everyone, and is often more fast-paced than a run-of-the-mill job

Some argue that ideal startup employees have to be better than the average worker at managing uncertainty, acting with an "ownership" mindset rather than being a cog in the machine, and pushing limits.

WeWork marketed itself on community

In a new era of work where many millennials wanted to work for themselves in offices with exposed brick, cold brew on tap, and casual dress codes, WeWork realized these entrepreneurs and startup workers didn’t want to do it alone.

How venture capital firms came to be

The venture capital firm that kickstarted an industry.

Burning Man has become a playground for Silicon Valley's tech workers, sometimes influencing the work culture of the country's biggest companies.

Silicon Valley’s reign over tech, money, and politics

Tesla and X CEO Elon Musk, OpenAI CEO Sam Altman, LinkedIn founder Reid Hoffman, and others are getting into politics. From Musk’s role in President Trump’s second term to Hoffman’s spending on former Vice President Harris’ presidential campaign, more tech CEOs are expanding into politics. This podcast episode by WBUR and American Public Media discusses what the impact could be with so many tech figures engaging in American politics. Listen here.

'Startups' can be defined as small, early-stage companies that are designed to grow fast.

The full story of WeWork, one of the most dramatic startup journeys of all time

WeWork has been through a lot since the office space company was founded as a startup in 2010. From its failed IPO in 2019, to the various leadership antics of its founder, Adam Neumann (some have claimed that he acted like a cult leader at times), to how it navigated remote work trends during the pandemic, this video tells the full story of WeWork's growth, failures, and more.

Many startups in a variety of industries try to reframe themselves as 'tech companies'

Tech is still the dominant industry for startups—in part due to its low barriers to entry, high growth potential, investor preferences, and the proliferation of tech into a wide variety of industries. Sweetgreen, the fast-casual salad chain, for instance, has often referred to itself as a tech company.

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.

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.

The evolution of X, from startup to Musk-owned giant, reflects rapid tech shifts

Twitter began in 2006 as a side project and grew into a major global platform, widely used for news, activism, and political discourse. Despite mainstream success, it faced ongoing management turmoil, business struggles, and rising concerns over misinformation and user safety.

In 2023, venture capital firms invested $170B in over 15,000 US companies

That's a significant drop from 2022’s $242B, reflecting market uncertainty but continuing VC’s role in scaling transformative ideas. Rooted in early risk-sharing models, venture capital took off with firms like ARDC in 1946, later evolving into today’s influential players like Sequoia Capital and Andreessen Horowitz.

Elon Musk's will to launch: the early days of SpaceX

Radically reducing the cost of rockets and innovating totally new space vehicles originated in the singular force of Elon Musk's vision. In this podcast, Founders creator David Senra shares what he learned reading a book about SpaceX's beginnings, highlighting Musk's audacious refusal to follow industry conventions and promotion of a culture of action and speed. Learn more insights from the founder here.

The infrastructure, talent, and markets of Silicon Valley make the high-tech region ideal for startups

The number of startup employees, founders, and investors who have flocked to Silicon Valley over the years makes the California region ideal for networking in the tech space. Plus, California’s laws and specific rules around trade secrets help founders of fledgling businesses in Silicon Valley feel protected.

Understanding TikTok-owner ByteDance's business model

ByteDance has ridden TikTok's major success to become the world's most valuable startup. This deep dive showcases some of the company's smartest moves and tactics, and where it's headed next.

Find out how venture capitalists make decisions

More than 30% of venture capital deals come from leads courtesy of a VC’s former colleagues or professional network. You can learn more about how venture capitalists decide which companies to invest in by reading this article.

‘I realized after I got there it was a cult,’ one former WeWork executive said

WeWork isn’t only known for how it revolutionized modern work, or its spectacular financial rise and fall. It’s also known for its former cultlike company culture under former CEO Adam Neumann, complete with a charismatic leader and “summer camp” company retreats that blurred the lines between work and personal life.

Startup founders’ equity becomes diluted as they bring in more investors

When an angel investor funds a company in exchange for equity, startups issue new shares to them, rather than giving them existing shares, and boost the company’s valuation.

X's quirky culture clashed hard with Elon Musk's extreme leadership style

Investigative journalists have written that social platform X's open, sometimes chaotic workplace stopped when control shifted irreversibly from Jack Dorsey to Elon Musk. They claim the stark contrast in personalities left little protection for existing employees, culture, or users.

See an analysis of the similarities between the characters in 'Silicon Valley' and the real people who inspired them

The HBO show "Silicon Valley" follows the story of an engineer who is trying to get his startup to take off in Silicon Valley. While one tech CEO said the show is like a documentary, many speculate the show is based on real life tech figures like Mark Zuckerberg and Peter Thiel.

Unlike small businesses, startups aim to disrupt entire industries

They also differ from small businesses in that startups have a higher level of risk, may take on outside funding from venture capital firms to boost growth, and more.