Google has established a long history of elaborate April Fools' Day pranks. But its most important April 1st announcement came 10 years ago today and centered around a very real product: Gmail. The leading email service was launched in beta form on April 1st, 2004. In the beginning, Gmail was an invite-only affair, and invites would remain the only way of signing up until 2007. (Thankfully they gradually got much easier to come by.)

Right from the start, Google took every opportunity to set itself apart from the competition. All users received a gigabyte of storage for their email, a massive figure that shamed what Microsoft's Hotmail and Yahoo Mail offered at the time. That meant most people would never need to worry about permanently deleting messages again. In some ways, it also ushered in the era of seemingly limitless cloud storage.

GmailoldGmail's interface as it appeared in 2004.

Most importantly, Google leveraged its search expertise to help users dig through their inboxes at lightning speed. But the wise early decisions didn't end there: email threads were presented neatly in a threaded conversation view, and Gmail users could send out attachments up to 25MB in size. Through the years, Gmail has evolved and seen numerous design changes — it finally dropped the "beta" label in 2009. Google's track record isn't perfect; last year's redesign brought on harsh feedback from some users.

Still, at its core Gmail still feels very much like the Gmail that launched in 2004. That remarkable consistency has undoubtedly been a huge factor in its continued success. But if things had gone differently, Google's big email bet might never have happened. To mark Gmail's 10th anniversary, Time put together a retrospective on its beginnings and earliest challenges.

Gmail