The Wall feature on Facebook allows users to post messages to their Facebook friends, either on their own Wall or their friends' Walls. The entire Facebook site was reformatted in late 2008; as a result, users are now able to post pictures, videos, and other multimedia on each others' Walls along with links and regular text. YouTube video clips are especially popular. The "Wall-to-Wall" feature allows users to view an entire Wall exchange between two users, regardless of how far back the log goes. Only users who are mutual friends or part of the same network can view each other's Wall-to-Wall, unless either user's privacy settings have been changed to dictate otherwise.

Walls are used for various purposes: idle chit-chat; chain letters and messages; plan-making; announcements; and more. Along with Facebook's Inbox and new IM feature, the Wall is the primary mode of user communication on the site. There is a character limit employed on Wall messages to prevent a single message from taking up too much space on a Wall; however, users can sidestep the feature by posting multiple messages as continuations of the others.