Gmail is a free, advertising-supported email service provided by Google.[5] Users may access Gmail as secure webmail,[6] as well as via POP3 or IMAP4 protocols.[7][8] Gmail started as an invitation-only beta release on April 1, 2004[9] and it became available to the general public on February 7, 2007, though still in beta status at that time.[10] The service was upgraded from beta status on July 7, 2009, along with the rest of the Google Apps suite.[11][12]

With an initial storage capacity offer of 1 GB per user, Gmail significantly increased the webmail standard for free storage from the 2 to 4 MB its competitors such as Hotmail offered at that time.[13] Individual Gmail messages, including attachments, may be up to 25 MB.[14] Gmail has a search-oriented interface and a "conversation view" similar to an Internet forum. Gmail is noted by web developers for its pioneering use of Ajax.[15] Gmail runs on Google GFE/2.0 on Linux.[16][17][18] As of February 2016, it was the most widely used web-based email provider with over 1 billion active users worldwide.[19][20] According to a 2014 estimate, 60% of mid-sized US companies were using Gmail.[21] In May 2014, Gmail became the first app on the Google Play Store to hit one billion installations on Android devices.[22]