Bandwidth :
Bandwidth can have many definitions relating to internet usage. When talking about
web hosting, bandwidth is the amount of bytes that is transmitted from the web server which has your web page files to the visitor's web browser. The larger the file size being transmitted, the more bandwidth it consumes. For example, the highest amount of bandwidth is usually used when displaying larger graphics on a web page or if a visitor downloads .zip or other binary files stored in your web space.
File / Data Transfer :
The larger the file, the more effort a server will need to take to "serve" the file (or send it) to the visitor's computer. This puts more load on the server. The server is quite fast and robust, so this is usually of no real concern to the web
website hosting owner. However,
website hostings which have very large files or a large amount of visitors downloading or viewing large files may cause the server to start to slow down. This can cause the web
website hosting (and others hosted on that particular server) to become slow to load or even inaccessible altogether.
To keep the bandwidth within reasonable amounts so that the server can work fast, some services charge for or restrict the amount of bandwidth that is used. For example, you may have seen some places advertise that you get 1 Gig of bandwidth per month. This means that no more than 1 Gigabyte of data (total files including binary and graphic files) can be transferred from your web
website hosting to a visitor's web browser in a month without possible extra charges or the
website hosting being shut down until the next month.