Content Management System
A webpage can be broken down into two main parts, the coding that structures the page and it's presentation, and the content therein.
Content Management Systems typically enable people who aren't designers or coders to produce or manage websites as they only have to put the content in promote whatever activity it is they want the website for.
A common drawback with many such sites is the content may be put in using fairly natural language, but we sometimes forget to put in the actual words that relate to our purpose.
I could wax lyrical about the "Bailey Unicorn Barcelona" for example, without mentioning it is a touring caravan.
OK a search for "Bailey Unicorn Barcelona" may find that webpage, on the other hand a searcher for caravans (a very competitive keyword) will not find you.