Publisher Summary Splitting operates, according to a technique that may widely vary from one method, from one device to the next. Splitting processes follow the same pattern. In the first, delimitation step, the batch L of matter to be sampled is virtually divided into a certain number, large or small, well defined or undefined of elementary units Um, according to a specific pattern. This step does not take the discrete structure of the material into account. In the second, extraction step, this virtual division is materially carried out. This second step does take the discrete structure of the material into account. In the third, distribution step, the elementary units Um are dealt out among a certain number N ≥ 2 of twin potential samples SA, SB, …, SN. This operation is specific of the method or device. The potential samples have approximately the same bulk and very similar properties. In the fourth, selection step, one or several actual samples Sk are selected from the set of N potential samples. This selection may be determinist or probabilistic, correct or incorrect.