Ad targeting in Gmail is fully automated, and no humans read your email in order to target advertisements or related information. This type of automated scanning is how many email services, not just Gmail, provide features like spam filtering and spell checking. Ads are selected for relevance and served by Google computers using the same contextual advertising technology that powers Google's AdSense program.

Privacy, Transparency and User Choice
Google does not and will never rent, sell or share information that personally identifies you for marketing purposes without your express permission. No email content or other personally identifiable information will be provided to advertisers. We provide advertisers only aggregated non-personal information such as the number of times one of their ads was clicked.

Only ads classified as Family-Safe are distributed through our content network and to your Gmail inbox. Also, we are careful about the types of content we serve ads against. For example, Google may block certain ads from running next to an email about catastrophic news. In addition, we will not target ads based on sensitive information, such as race, religion, sexual orientation, health, or sensitive financial categories.

You can control the use of these signals from the Gmail Settings page. If you don't want to see ads in Gmail you have the option of using the HTML interface, or POP1 or IMAP. We're also committed to data liberation: if you decide to switch to a new email provider, it's easy to set up automatic forwarding for all new messages that arrive in your Gmail account.