The Gmail Labs feature, introduced on June 5, 2008, allows users to test new or experimental features of Gmail.
Users can enable or disable Labs features selectively and provide feedback about each of them.
This advertising practice has been significantly criticized by privacy advocates due to concerns over unlimited data retention, ease of monitoring by third parties, users of other email providers not having agreed to the policy upon sending emails to Gmail addresses, and the potential for Google to change its policies to further decrease privacy by combining information with other Google data usage.
The company has been the subject of lawsuits concerning the issues.
The service is notable among website developers for its early adoption of Ajax.
Google's mail servers automatically scan emails for multiple purposes, including to filter spam and malware, and to add context-sensitive advertisements next to emails.
In May 2013, Google updated the Gmail inbox with tabs which allow the application to categorize the user's emails.The five tabs are: Primary, Social, Promotions, Updates, and Forums.In addition to customization options, the entire update can be disabled, allowing users to return to the traditional inbox structure.In order to send larger files, users can insert files from Google Drive into the message.Gmail has a search-oriented interface and a "conversation view" similar to an Internet forum.Other updates include a Confidential mode, which allows the sender to set an expiration date for a sensitive message or to revoke it entirely, integrated rights management and two-factor authentication.