Just like bandwidth, web space is essentially and undisputedly – limited. Hard disks have limited capacities, and although those hosts who offer unlimited space might argue that hard disks can be added when necessary, fact is that even then, the space would be limited.
Unlimited space usually comes with other limits stipulated in the terms of service, such as a maximum of inodes (files and directories), limits or bans on the use of space to store multimedia files, personal backups etc. So, you should read the terms carefully. For the vast majority of website owners, the limits will be more than acceptable, and you run no risk of having to pay for extra space usage either.
Truth be told most all companies that offer this have a hidden limit you don't see until you reach it. We show our limits upfront so you always know where you stand. To help you with space here is a tip for picture uploads also found in our bandwidth question because it effects both areas. Most pictures taken from a camera will be about 100 to 200 meg or more depending on the pixel size. If you have resized the picture with an editor before uploading it, it will drop the picture to less than a meg in size depending on the size you made it. A picture of about 480px × 320px will be 78.85 KB (80,738 bytes). Resizing your pictures will save you a ton of space and bandwidth. If you need help in this area just put in a support ticket and we will help you to make you site space and BW Friendly.