Every hosting account has a certain amount allotment of disk space. The disk space is used to hold all the files which make up your web site, HTML files, graphics, scripts, and multi-media content. Usually the more expensive the hosting package the more disk space and the more bandwidth you receive
Data Transfer in its simplest terms refers to the amount of data that flows across a network wire in a given time period. For most web hosting providers, that time period is measured in a month. Web hosting providers are charged a certain amount per month or per year for an allocated amount of bandwidth from backbone providers and wholesale data centers. That cost is then passed on to the consumer in the form of web hosting plans.
One of the processes of setting up a website is to transfer files from your computer to the Hosting Server. To do this an FTP User is created and asigned a password and username. The user through FTP Software is able to log in and bulk transfer the files for the website.