CMS - Content Management System
CMS is a collection of tools designed to allow the creation, modification organisation and removal of information from a Web site. It is common for a CMS to require users to have no knowledge of HTML in order to create new Web pages.
Blog - We(b Log)
A blog is a web page made up of usually short, frequently updated posts that are arranged chronologically—like a what's new page or a journal. The content and purposes of blogs varies greatly—from links and commentary about other web sites, to news about a company, person or idea.
Blogs are typically updated daily using software that allows people with little or no technical background to update and maintain the blog.
Wiki
A wiki (Hawaiian for rapidly) is a web application that allows users to add content, as on an Internet forum, but also allows anyone to edit the content. Wiki also refers to the collaborative software used to create such a website.