When you click Like on a Facebook Page, in an advertisement, or on content off of Facebook, you are...
When you click Like on a Facebook Page, in an advertisement, or on content off of Facebook, you are making a connection. A story about your like will appear on your Wall (timeline) and may also appear in News Feed. You may be displayed on the Page you connected to, in advertisements about that Page, or in social plugins next to the content you like.
Facebook Pages you like may post updates to your News Feed or send you messages. Your connection to the page may also be shared with apps on the Facebook Platform.