We live in the era of high technologies, and we use modern inventions in our everyday life because they have brought us much comfort. New technologies have spread on every field over the past 15 years. Moreover, they are rapidly changing. For example, video-recorders, DVD-players or compact disks have already become obsolete and have been replaced by more up-to-date devices. Today we can hardly imagine our life without such modern mobile devices as cell phones or laptops. Our offices are fully equipped with computers, printers, scanners, air-conditioners, interactive whiteboards and wi-fi modems. Household appliances (vacuum-cleaners, coffee-machines, dish-washers, food processors and others) help us to save our time and energy.