What are they and why use them?

They are used for the development of web sites.

Up until now I have used 'Front Page' to build websites but it seems that technology has now made this a redundant programme.

For example a web page is made up of instructions (xhtml) to tell the browser how to display the page. (Static web page). This is an outdated way of doing things and has two main drawbacks. Th presentation and the content are tied together, also the page size is large which means lots of data to download.

Content management has evolved due to the recent (last 4-5 years) development of Cascading Style Sheets (CSS). CSS controls the visual presentation of the page. This is a small file containing data on fonts, colours, spacing, etc. This makes updating the site much easier as one line change does the whole web site. A CSS file has the advantage that it is 'cached' once on to your browser, so makes the viewing of a page much quicker. So CSS separates the content from the presentational aspects of the page.

CMS then goes one further and separates the content from the page. What is left behind is the place holders that the CMS uses. It grabs the content from the database and puts it where it supposed to go . This separates the presentation/design from the content. This means that someone can do the graphic design leaving an author to write content. The CMS makes the pages dynamically. They don't exist until you follow the link to view them.

Seems very strange that you cannot 'look' at the pages with a file manger, they just do not exist. The are generated each time using the CMS.

Content Management Systems page 2