Like or unlike

Liking a post (story) shared by a coworker you are following says this information is important to you and you agree with your coworker's idea or assessment.

To like a story, select Like in the story summary or tap Like on the action menu of the Wall view.

When you like someone's post, your coworker may be notified of your action, giving him or her the opportunity to respond. If you want to change your assessment later, you can Unlike the story.  

TIP	To receive notifications when coworkers like your posts or comments, or comments on a story you liked, change your account settings.