A monograph entitled "Theory and Application of Artificial Intelligence Methods (TAAIM)" is the first book in a series of monographs entitled "Intelligent Systems and Information Technologies (ISIT)", in which we want to publish extended research results previously discussed at the Scientific Seminars of the Institute of Computer Science of the Siedlce University of Natural Sciences and Humanities, or at scientific conferences entitled Intelligent Systems and Information Technologies and published in the scientific journal of our University entitled "Informatica studies. Intelligent Systems and Information Technologies", and then highlighted with a proposal to prepare an extended version of the article in the form of a chapter to the monograph. The current monograph consists of six chapters covering important and current issues of the theory and applications of artificial intelligence methods, such as: the results of comparative research on selected methods of cluster analysis, which were carried out from the point of view of their use in the analysis of clusters regarding the operation of the National Power System by Dr Hab. Eng. Jerzy Tchórzewski and MSc. Tomasz Kania, the use of True- Range multilateration and low-energy Bluetooth transmitters for user positioning in rooms using a smart mobile device by MSc. Tomasz Żochowski and PhD Dariusz Mikułowski, spam detection using artificial neural networks by PhD Piotr Świtalski and MSc. Mateusz Kopówka, neural modeling on the example of the Day-Ahead Market system of TGE S.A. by MSc. Dariusz Ruciński, automation of processes related to Internet of Things systems by MSc. Kamil Skarżyński, PhD Waldemar Bartyna, and PhD Marcin Stępniak, and the complexity of protecting ICT systems in public administration from the point of view of cybersecurity by PhD Tomasz Muliński.