Sampling

Sampling could mean:

Sampling (signal processing), changing a continuous signal into a discrete signal
Sampling (music), re-using parts of sound recordings in a piece of music
Sample (statistics), selection of observations to get some knowledge of a statistical population
Sampling (case studies), selection of cases for single or multiple case studies
Sampling (for testing or analysis), taking a representative portion of a material or product to test (e.g. by phyisical measurements, chemical analysis, microbiological examination), typically for the purposes of identification, quality control, or regulatory assessment 

Specific types of sampling include:
Chorionic villus sampling, a method of detecting fetal abnormalities
Food sampling, the process of taking a representative portion of a food for analysis, usually to test for quality, safety or compositional compliance. (Not to be confused with Food, free samples, a method of promoting food items to consumers) 
Theoretical sampling, the process of selecting comparison cases or sites in qualitative research
Water sampling, the process of taking a portion of drinking water for analysis, e.g. to check that it complies with relevate water quality standards, or river water to check for pollutants, or bathing water to sheck that it is safe for bathing, or intrusive water in a building to identify its source.