Like ......
I see the "like" button as a way of acknowledging to the writer that you have read their message as well as communicating to the writer and the reader that you either appreciate the information in the post or you endorse it. In these cases it cuts down on time to write and read a regular post.
Not like .......
I see the " not like" button as a way of acknowledging to the writer that you have read their message as well as communicating to the writer and the reader that you do not appreciate the information in the post, nor do you endorse it. In these cases it cuts down on time to write and read a regular post.