At fi rst, the number of people on email was small, but by the end of the 20th century, there were 263
million email boxes. In the 21st century, that fi gure has grown to over 2 billion, and the functions of
email services in the future will become more and more diversifi ed. And text messaging on cell phones
is also increasing, so people can, in eff ect, be in constant touch with people who are long distances away.