In the 21st century, it is a must for economic actors to get involved in some forms of information and communication technology. It is equally true that it is difficult to know our way around in the vast labyrinth of the ever more complex technological systems. This study aims at highlighting the intensifying relationship between the role of information and communication technology and the daily operation of enterprises by researching into the effects of the information society on the Hungarian economic sectors. Apart from examining the requirements of the information society, the ICT development levels of the individual economic sectors and company size categories are also investigated and compared to each other as well as to other member states of the European Union. Heading from the general to the specific, a case study is included to reveal the background criteria for making decisions on introducing and implementing business information systems in terms of the various needs and size categories of enterprises, discussing the factors contributing to the increase in the operational effectiveness of enterprises in more detail.