For experimental purposes, cells are often cultivated in containers that take the form of plastic flasks or plates. In such flasks, cells are provided with growth medium comprised of the essential nutrients required for proliferation, and the cells adhere to the container and each other as they grow.
This process of cell culture or tissue culture, requires a method to dissociate the cells from the container and each other. Trypsin, an enzyme commonly found in the digestive tract, can be used to "digest" the proteins that facilitate adhesion to the container and inter-cellularly.
The process of trypsinization is often done to permit passaging the cells to a new container, observation for experimentation or reduction of the degree of confluency in the flask by removal of a percentage of the cells.