If you are thinking about starting a blog or already have one on a free service such as Tumblr or Wordpress, you may have the itch to get your very own domain name.
In internet language... the term theme refers to the look and feel of a website. It's a mixture of graphics, colors, fonts, and the page layout that give a website a unique look. For example, if you think of a car... the body styling, the shape, and the colors are the "theme." The frame and engine of the car are separate, they are not part of the theme.