Do you know when orange is the new black? When pleats are in style? Then you must follow fashion — you observe it closely. Follow can also mean you trail along behind someone. You might follow your brother to school.
If you follow something, such as line of argument, that means you understand it. If you follow through on something, such as a diet, that means you stick to it. Follow can also describe a sequence of events. Your election as class president might follow a scandal involving your opponent. Follow can also mean something is a logical consequence of something else. It follows that having read these examples you now understand the various meanings of follow. You follow me?