Get on the net and find your true identity
On the negative side, it provides a platform for propaganda and misinformation, bombards users with trashy and offensive material, and offers scope for various forms of exploitation.
Parents and teachers are naturally concerned to protect children and young people from the potentially harmful effects. Equally, many young people themselves are keen to explore the full potential of the technology and to test the limits which adults consider appropriate, even if that sometimes involves taking risks.
One aspect which has perhaps received less attention than it deserves is the effect on personal identity. Our conception of human character has been subject to major change over the past 200 years and the internet is introducing new dimensions. In the 19th century, it was assumed that identity was relatively "fixed". This can be seen in the great novels of the period in which characters may sometimes lose their way for a time but eventually find their "true selves". Innovative 20th century writers, influenced by Freudian psychology, offer a much more fluid and elusive view of human character and indeed often present the search for identity as a never-ending quest.
The internet offers a further, and possibly more fundamental, challenge to our conception of identity. Its anonymity enables people to explore aspects of themselves that ordinary social relations do not readily allow. They can set up multiple screen names, create fictitious profiles of themselves and enter chatrooms where they can present themselves in ways that their friends and families might not recognise. In a sense, they can become whoever they want to be.
It is this capacity, in an extreme form, that enables the paedophile to pretend to be a young person and groom intended victims. But the capacity is not confined to those who are intent on sexual abuse. It can be used for all sorts of purposes and, like the internet itself, these are double-edged in their effects.
Consider the adolescent, trying to make sense of his or her experience, and uncertain of what the future holds in terms of employment, lifestyle and personal relations. The internet offers a tool of enquiry where various possibilities can be explored without the risk of social embarrassment that often accompanies such tentative efforts in "real" life.
Again, where youngsters feel unduly constrained by the expectations of adults that they will conform to particular norms, the internet can provide an outlet for their alternative interests and aspirations. The danger, of course, is that fantasy takes over and they develop a view of themselves that lacks substance. Serious psychological disjunction can follow.
These tendencies can be related to wider trends in society. The sociologist Zygmunt Bauman argues that, in an age of change and disposability, human identity has become transient and precarious. This has implications for the way in which people see themselves in all aspects of their lives - whether political, professional, religious, sexual or cultural.
As yet, we do not fully understand where all this will take us. But surely it requires serious attention by those of us involved in education. If the old certainties about human character are no longer valid, what reference points can we use as a basis for the way in which we treat young people? The ambivalence of the internet may force us to address this question.
Walter Humes is professor of education at Aberdeen University.