Definition of a Facebook Share
The definition of what a Facebook share like is.
A facebook share is when you click the share button to share a piece of content on Facebook. The share button can be clicked on Facebook and or on someone's website. By adding a special code to a web page you can place a Facebook share button on your web page. When the share button is clicked and the share is posted, the shared content is then published to that user's personal profile (Facebook calls this your "wall"). Once it's published there, that user's friends will then be shown the shared content when they view Facebook's home page and when they view that user's profile page.
Below is an example of what it may look like when you click the share button just before you approve it to be published on your profile on Facebook.