I am having some trouble understanding the exact difference between the do_action and add_action functions. I've searched google and these forums, still am confused. Codex does not help me either.
I understand the add_action function for writing a plugin that does something at a certain point in the WordPress flow using a call back function.
But what is do_action? I see no callback function or anything when these are used. I guess I don't get the exact difference between the two and moreso the point or use of do_action when writing a custom plugin?
Help from someone with more working knowledge than me explain the simple difference I am not able to grasp?