This guide covers the awareness and use of available standard methods for characterizing solid and liquid particles, and provides information for subsequent evaluation and standardization. The principal purpose of this guide is the identification of particle characterization standard methods that have been developed and published by various standards organizations worldwide. Although this is an extensive list of methods, it is not all inclusive. WD working drafts, CD committee drafts, DIS draft International Standards and FDIS final Draft International Standards may not be completed documents. These standards have been divided into the following twelve sections related to particle characterization.