This document provides an overview of sorption isotherms and several methods used to measure them. It defines sorption as a physical or chemical process by which one substance becomes attached to another, such as liquids being absorbed by solids or gases being absorbed by liquids. The document then discusses sorption isotherms and their typical shapes before describing three common methods used to measure sorption isotherms: the gravimetric method, manometric method, and hygrometric method. It provides details on the basic principles and procedures for each measurement technique.