This chapter outlines the requirements for sample preparation for solid, liquid, and gaseous samples and details a range of equipment and methodologies used for sample preparation. It examines the development of appropriate sample preparation strategies for samples with varying requirements. It also describes the sample preparation wherein the analyst has to identify the necessary procedures and perform them so that the analyte or property can be readily measured using the chosen method of analysis. The chapter emphasizes how the processes of sample preparation and measurement must be chosen very carefully in order to answer the problem correctly. It discusses how knowing the chemical make-up of the matrix helps formulate how an analyte can be released from the sample itself.