Does Sending a Message on Facebook Show Up on a Wall?

Facebook's Messages screen includes both asynchronous conversations sent while contacts are offline (similar to email) and chat conversations sent in real-time (similar to traditional instant messaging programs). Messages sent through the Messages screen, the Chat sidebar or Facebook's mobile applications are kept private and can only be seen by the sender and the chosen recipients.

Facebook's messaging system is completely closed -- there are no privacy settings that can be tweaked to expose your conversations with others, nor can anyone else see who you are communicating with. If you're replying to an existing message, check the list of recipients at the top of the conversation to make sure you're aware of the Facebook friends who will receive it. These private messages do not appear anywhere else on Facebook, though be aware that anyone you send a message to could choose to forward it on to someone else.

The only messages that appear on a Facebook wall or Timeline have been posted there directly using the "Post" box at the top of the page. These posts typically show up for anyone who visits the Timeline, and may appear in the news feeds of your friends too. This method is more suitable for messages that aren't private and when other mutual friends may want to view or join in with the conversation.

When you post a message on someone else's Timeline rather than through the Messages screen, the friend in question has control over who can see the post via the Timeline and Tagging settings. You will therefore not be able to restrict who is able to view it -- typically, all of your friend's friends have access to it if they choose to visit the relevant Timeline. Whether the post shows up in your friends' news feeds depends on several different factors, including the news feed settings configured by each friend.