The purpose of kraft pulping is to separate fibers from each other so that they can be used to produce paper and other cellulose fiber based products. This type of chemical pulping is accomplished by cooking wood chips in a chemical solution in large pressure vessels called digesters. Pulping can be performed in digesters running in batch or continuous mode. This module describes the advantages and disadvantages of different types of digesters, including: batch systems, continuous cooking systems with one and two vessels, continuous digesters which are hydraulically filled and those which utilize a vapor phase. Pandia and M&D digesters are also described.