This paper intends to precisiate the well-known and widespread definitions of both smart and intelligent agent (SA; IA), as well as the smart and intelligent multi agent system (SS/II_MAS). The use of a unified and standardized agent and multi agent system description based on definitions of the general systems theory is delivered and proposed as well. The intellectics of multi agent systems is considered as some sort of an extension of the agent intelligence. Three typical features of human intellectual activities are proposed to be implemented and simulated in an agent/multi agent system as the basic paradigms for agent and multi agent system intellectics. As underlined in the paper, the functioning according to those paradigms (recognition and classification, behavior according to a set of fuzzy rules, and the functioning according to some prescribed tendency) is solidly mathematically based (correspondingly: mathematical programing, fuzzy logic and stochastic approximation). Finally, results of a computerized modeling and simulation are delivered demonstrating the practical vitality and efficiency of the theoretical approach to the realization of the intelligent environment of IoT&S for user‘s comfort in two projects: “Research and Development of Internet Infrastructure for IoT& S in the Smart Environment (IDAPI)” and “Research on Smart Home Environment and Development of Intelligent Technologies (BIATech)”. DOI: http://dx.doi.org/10.5755/j01.itc.44.1.8768