The most successful startup depends on how you define success. Some people might consider the most successful startup to be the one that made the most money, while others might consider it to be the one that changed the landscape the most or had the most impact.
Here are a few examples of startups that could be considered successful, based on different criteria:
Apple: one of the most successful companies in the world, valued at over $1 trillion
Google: changed the way we use the internet and now has over 1 billion users
Uber: disrupted the transportation industry and is now valued at over $70 billion
Airbnb: created a new way to travel and is now valued at over $31 billion