You have probably noticed the Thanks button and the '+' and '-' signs. Well, i will explain this with examples.
Liking
This user has a reputation of 0:
And his reputation goes to 1:
And if I don't like the message :
His reputation goes back to 0:
Liking
This user has a reputation of 0:
And his reputation goes to 1:
And if I don't like the message :
His reputation goes back to 0: