Plastics are extensively used across various sectors, including agriculture, industries, construction, and daily life, owing to their low cost and excellent corrosion resistance. However, this widespread use has led to a significant accumulation of plastics released into the environment, coupled with growing concerns about its potential harm to biota has made plastic waste an escalating issue worldwide. Under environmental stress, plastics break down into micro- and nano-plastics (MNPs), which vary in size, shape, morphology, and composition. Despite growing concerns, research on effective methods for collecting and separating MNPs remains limited. This chapter outlines the sampling procedures for MNPs from both environmental and biological sources. It then explores the methods for extracting and separating MNPs, followed by an in-depth examination of the techniques used to identify and quantify these particles. Finally, the review discusses the need for standardized and harmonized approaches for the separation, extraction, and identification of MNPs, aiming to provide a framework for advancing pollution monitoring and risk assessment of MNPs in the future.