Web pages are made of a series of web technologies.  They are combined to get the desired results.

A web page could be static or dynamic.

A static web page is the one that does not do anything, but to inform.  It has links that go to other pages or websites.  It also contains images.

The only form allowed in static pages is the old fashion email form.

Among dynamic content is flash, e-commerce, user-feedback, communities, etc.

The website could be done by using a CMS or it may need to be customize to your needs.

When a developer has to create from scratch.  Obviously, it takes longer to produce a work and lot's of planning.

In this case, the price of the product is allways higher.