After few research in Google and Yahoo, i finally realized the importance of labels/categories in your blog post.
But first, lets take a moment to examine what categories and tags are.
What are Categories and Tags?
I think categories as the table of contents for your blog, a kind of general outline that directs visitors to general topics that you blog about. Tags are more like the index page of a book, a list of key words people will use to search for specific terms.
But the what is the real purpose of tagging and putting it into categories?
If you ask me, it serves only 1 purpose, helping your readers find the information they need on your blog.