What is a Blog?
A blog is something which someone updates on a regular basis and provides the appropriate information for that blog. Each blog will be about something else, and a blog is usually about someones interests and the follewers of that blog are interested in that as well. For example a blog can be about sports and another blog may be about music. Anyone can make a blog for free and talk about anything that they like. A blog also has to be regularly updated so that the followers of that blog won't lose interest in it.
What is an RSS Reader and Why use it?
An RSS Reader is something that allows people to follow other peoples blogs and get notified through the RSS Reader on when someone updates that blog. It also means that if you want to follow a large amount of blogs, they are all in one place instead of you having to find them again. An RSS Reader also allows you to go directly to a blog.