Which are the most successful companies to graduate from Y Combinator?

Oh, speaking of Y Combinator (YC for short), it has produced so many incredible companies, truly earning its reputation as the "Whampoa Military Academy" of the startup world. When it comes to the most successful, the criteria might vary. Is it about the highest valuation, or the greatest impact on our daily lives? However, there are a few universally recognized ones that you've probably heard of or even used to some extent.

1. Airbnb This is arguably one of the most famous. Simply put, it allows you to rent spare rooms or entire homes from others when you travel, instead of staying in a hotel. It has fundamentally redefined travel accommodation.

2. Stripe You might not have directly used this company, but it's behind many of the websites and apps you use for daily purchases. It's a payment processing platform that enables internet companies of all sizes to easily accept online payments. Though it maintains a low profile, it's a fintech giant with an extremely high valuation.

3. Dropbox This one is also very well-known, and can be thought of as a "cloud USB drive." You drag files into a folder on your computer, and it automatically syncs them to the cloud, allowing you to access them on your phone, tablet, or any other computer. It was definitely a star product when cloud storage was first emerging.

4. DoorDash The American equivalent of "Ele.me" (a Chinese food delivery service). You tap on your phone, and restaurant food is delivered right to your doorstep. It's now one of the leading players in the US food delivery market.

5. Coinbase If you follow cryptocurrencies like Bitcoin and Ethereum, then you definitely know Coinbase. It's one of the world's largest cryptocurrency exchanges, making it easy for ordinary people to buy, sell, and manage digital assets.

6. Reddit It can be understood as a massive collection of "Tieba" (a Chinese online community platform) in the US. Users create communities (called subreddits) on various topics, discussing everything from serious tech news to cute cat pictures, covering a wide range of subjects. It's the birthplace of much internet popular culture and many news events.

7. Instacart This is an "online grocery shopper service." You place an order online for groceries and household items, and then a "shopper" goes to the supermarket to buy them for you and deliver them to your home. Especially during the pandemic, it became an essential service for many households.

Of course, this is just the tip of the iceberg. YC has graduated thousands of companies, and many others, while not as widely known as those listed above, are absolute leaders in their respective specialized fields. YC's brilliance lies not only in incubating these giants but also in fostering a vast and mutually supportive alumni network.