The document discusses different sampling techniques and sample types used in research studies. It describes key concepts like target population, study population, and sampling frame. There are two main types of sampling techniques - probability sampling and non-probability sampling. Probability sampling aims to achieve a representative sample and includes random sampling, stratified random sampling, cluster sampling, and systematic sampling. Non-probability sampling includes convenience sampling, purposive sampling, and quota sampling. The document provides details on several specific sampling strategies under qualitative research.