Under the term information system one part of the real organisation system which serves during conversion of input information into output information. Information system is a formal part of communication system within a specific business unit and consists of a group of people and machines processing information. Businessinformation system serves as help during decision making process in the way that it helps managers making their decisions by providing them with necessary information and giving them solutions for optimisation problems. Business information system itself can even make decisions on its own for repeated situations. Information systems serving as business support are called business information systems. Business information system helps during the decision making process in the way that it helps managers make their decisions by providing them with necessary information and giving solutions for optimisation problems. Business information system can even make decisions on its own during anticipated repeated situations. Business information systems consist of five basic components: material-technical components, non-material components, human components, network components, and organisation components. They carry out key functions , such as the function of preparing the information base for the purposes of making decisions and documenting permanent information storing. Information basis key features are quality excellence,quantity, and value of information in time. Business information system, like every other system, has its lifespan. The essence of a lifespan of a business information system is comprehension according to which each system of this kind is created within a certain point in time, and develops afterwards consistently with certain legalities in order to disappear after certain amount of time be replaced with another new system.