Disk space is the amount of storage a web host allocates to its client according to the hosting plan he/she has subscribed. Usually the web pages are of smaller size and small amount of space can store several pages, if the website allows users to upload files, contribute data (Images, Videos etc) or if your website is having a large database you need to look for a hosting plan which can facilitate your requirements of disk space.  Disk space is stated in bytes, kilobytes and megabytes.