Many web hosts offer unlimited features such as web space and bandwidth. Unfortunately, no such thing exists. Unlimited plans are marketed towards the lower end of the hosting market (i.e. newbies) who are unsure about how web hosting works.
The truth is, no web hosting service can offer unlimited bandwidth or webspace, least of all those who only charge a few dollars a month for hosting.
Hidden in their terms and conditions will be a fair usage policy of some sorts and if your blog does start getting heavy traffic, you will be asked to update to a more expensive package or your hosting will be switched off.
This is nothing against web hosting companies. I understand why they market in this way because many people have no idea of how hosting works. Hosting companies realise that the majority of people who purchase cheap hosting deals only require a little webspace and a low amount of bandwidth so most of them will not even realise that they do not have an unlimited amount of webspace.
This does not mean that a deal which promises unlimited features is not good value. What the host can offer is a reasonable amount of bandwidth and webspace which is more than sufficient for starting a blog.
Just be aware that you do not actually have an unlimited amount of webspace or bandwidth with your package. If you don’t believe me, try uploading some large video files for your users to your blog and see how long it takes for your host to contact you about you exceeding your bandwidth limits!!