This document defines routes of administration and classifies them as topical, oral, parenteral, rectal, and inhalation. It provides details on each route, including advantages and disadvantages. The oral route is intended for systemic effects and has benefits of convenience and variety but can be inefficient due to first-pass metabolism and food interactions. Parenteral routes like intravenous provide precise dosing but risks of embolism. Inhalation provides a rapid onset due to the large lung surface area.