This article provides more information about neural network technologies and how they are used. The authors provide important information on boosting algorithms, using genetic algorithms, minimum spanning trees, and clustering algorithms. The use of neural networks in the classification of electronic document flow attracts more developers of tools. Neural network mathematical models and their working principles are correctly shown. In particular, the formulas and functions of the input and output mechanics of the neural network are described. This information can be useful for learning and researching neural network technologies.