Web conferencing is used to conduct live meetings or presentations over the Internet.

Advantages

• travel at lightspeed - webconferences can substitute for f2f meetings when travel costs would be large.
• shares slides, graphics and other images in realtime during the conference. Some tools have an on-line 'whiteboard' that facilitates interactive graphical 'scribbling' by the group.
• best used in tandem with a conference call.
• The technology is scalable - it can go from a 1-1 to a mass meeting with several hundreds of participants.
• Convenience - commercial services such as IBM/Lotus Quickplace, Webex, and others provide realtively easy to use and relatively reasonably priced services.
• Can include community workplaces, threaded discussions, news streams, meeting agendas.

Disadvantages

• lack of f2f and other non-verbal communication (unless the technology includes video conferencing.)
• services can be pricey for small businesses
• session data / questions / discussion may not be retained after the conference is over.

Best Practices

• webconferences are best used for demonstrations and training where new-potential users can see processes happening in real time.
• when used for meetings, get participants to print out the agenda and calling instructions beforehand.

For details see: http://en.wikipedia.org/wiki/Web_conferencing