When Gmail was released to the public on April 1, 2004, many people thought it was a prank. Gmail offered one gigabyte of storage and robust email search. These features, among others, have helped to make Gmail the most used email service in the world with 1.5 billion users. Gmail has come a long way since its inception. It stands as the most dominant online email service with more than 1.5 billion global active users. It has gone from a small experiment to an important piece of Google's G Suite lineup. But the road to the top hasn't been without a few bumps, including a rocky start. By the time Google started working on the service in 1999, Yahoo Mail already had 12 million active users and Microsoft's Hotmail had about 30 million. Paul Buchheit, who was employee No. 23 at Google, fought for the online email service, but executives didn't understand how a search company could benefit from online email. Some executives pushed back at the time, according to multiple reports. Buchheit created the service as a "20%" project, which is an informal program Google has sometimes offered employees to work on projects of their choosing. When Gmail actually launched, people thought it was a joke -- literally. Becaase it was announced on April Fool's Day 2004, people wondered whether the company was pulling one over them. But once users realized it was real, it became one of a number of free email services alongside Microsoft's Hotmail and Yahoo Mail, which were some of the first to introduce web-based email in the 1990s. Monetizing Gmail has been a point of contention within the company. Some people argued that in order for Gmail to have the most reach, it needed to be supported by advertising, rather than user subscription fees. The ad model won out but, even before it launched to the general public in 2007, Google got heat for scanning Gmail emails and using the contents for targeted advertising. The company drew scrutiny again in 2018 after Google admitted to allowing app developers scan Gmail accounts for ad targeting. It would come up again through 2019 as Congress grilled Google alongside other tech companies over privacy. Over the summer, the company admitted to keeping a list of items users purchase using Gmail. Even though the email service didn't start doing exceedingly well compared to competition until 2012, it continues to innovate. The company still aggressively targets both consumer and enterprise users. It also continues to add innovative new features such as Smart Compose, which uses artificial intelligence to predict responses.