Almost half the universities and colleges in the United States now offer courses through the internet or videoconferencing.

A survey from the US Department of Education shows that online courses are becoming part of the mainstream of higher education, with "non-traditional" teaching mediums growing in popularity.

The number of colleges offer distance-learning courses, both online and using the post, has grown rapidly - rising by a third in three years to 79%. The most recent figures, for 1998, show 1.6m students enrolled on distance-learning courses.

And among this total of colleges offering distance learning, the proportion using the internet has grown from 22% in 1995 to 60% in 1998. The survey says that this figure is projected to continue rising, as universities say they plan to expand the courses available through the internet.

Apart from the development of the internet, the growth has been attributed to the increasing number of adults wanting to study - particularly in work-related subjects.

Adult students want to be able to access coursework from home and at times that can be fitted around work - and the internet and e-mail provide flexible ways for students to receive and submit work.

There are also savings for universities, with 'virtual' courses costing less in terms of premises and administration.

The use of the internet for recruiting students has also grown, with an increasing number of institutions accepting applications via e-mail or providing an online applications form.