Blogs are basically an online log of your live weblog. People make them for various reasons, mainly for updating people of their lives, could be for family members, people travelling, musicians, a plethora of reasons.

You don't need anything to do them, just an online account somewhere to host it.

Blogs and vlogs are made up of anything, text, pictures, music - anything you feel people might be interested in reading.

People like to make their lives public, really going back to th first point. If they are up to something where others might be interested etc.