Fischer Esterification is also known as acid-catalyzed esterification. Why is it so important? Because we convert an OH group to an OR group.
Concept #1: General Reaction
Concept #2: General Mechanism
BTW if you notice that when drawing the first resonance structure in red there is an arrow that looks off, don't be alarmed! The arrow should go the opposite direction [from the double bond to the +OH group]