Gmail is a mailbox provider by Google. It is the largest email service worldwide, with 1.8 billion users. It is accessible via a web browser (webmail), mobile app, or through third-party email clients via the POP and IMAP protocols. Users can also connect non-Gmail e-mail accounts to their Gmail inbox. The service was launched as Google Mail in a beta version in 2004. It came out of beta in 2009.

The service includes 15 gigabytes of storage for free for individual users, which includes any use by other Google services such as Google Drive and Google Photos; the limit can be increased via a paid subscription to Google One. Users can receive emails up to 50 megabytes in size, including attachments, and can send emails up to 25 megabytes in size. Gmail supports integration with Google Drive, allowing for larger attachments. The Gmail interface has a search engine and supports a "conversation view" similar to an Internet forum. The service is notable among website developers for its early adoption of Ajax.

Google's mail servers automatically scan emails to filter spam and malware.