The worldwide web is an online information source that can be accessed by users of the Internet. It is used by organisations to sell their merchandise, and by institutions and others to promote their activities: new uses for it are growing daily. Web designers and webmasters are involved in the design and realisation of websites. They discuss with the client how best to make his website include all that is required, estimate the cost involved, and decide how to incorporate the audio and video material. They then upload the pages on to a server, and may help to keep the site up to date. They also train the client in how to use the system.