A Primer on Unimodular Gravity

We give a basic introduction to Unimodular Gravity both at the classical and quantum level, discussing the paper it might play in the interpretation of the Cosmological Constant problem. The aim of this work is at the basic level but techniques used at the research level are presented. The goal of the paper is to enable the reader to grasp the interest of UG while making the recent literature on the topic accessible.