Ads in Gmail and your personal data

How Gmail Ads work

Ads that appear next to Gmail messages are similar to the ads that appear next to Google search results and on content pages throughout the web. In Gmail, ads are related to the content of your messages. Our goal is to provide Gmail users with ads that are useful and relevant to their interests.
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. Google provides advertisers only aggregated non-personal information such as the number of times one of their ads was clicked.
Privacy is an issue google takes very seriously. Only ads classified as Family-Safe are distributed through our content network and to your Gmail inbox. Also, they are careful about the types of content they serve ads against. For example, Google may block certain ads from running next to an email about catastrophic news.
If you don't want to see ads in Gmail you have the option of using the HTML interface, or POP 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."-google sources
If you'd like to know more about how Google handles your information, please check out the Google Privacy Center.