Step 1: Understand that a functional group is a specific group of atoms within a molecule that is responsible for the chemical properties of that molecule.
Step 2: Learn that esters are a type of organic compound.
Step 3: Identify the structure of the ester functional group, which is RCOOR'.
Step 4: Recognize that 'R' and 'R'' represent hydrocarbon chains, which can be different lengths and structures.
Step 5: Conclude that the ester functional group is characterized by the presence of a carbonyl group (C=O) and an ether group (C-O) connected to it.
