What is meant by content management?How it is done?
Thanks in advance.
Content management means a lot of different things. At the base level, it simply means a method of managing content. The goal is usually to arrive at a system whereby content authors can add, edit and remove content from a content delivery system (like a website) without having a great deal of knowledge about that system (such as knowing how to write HTML).
There are a lot of ways to handle content management, ranging from template languages to database-driven forms, to cached results. There are a lot of different solutions to achive this. It's not really a topic that can be easily covered in a few paragraphs.