Each time any data is sent to or from your site, it is transferred across the Internet and this is referred to as 'data transfer' or 'bandwidth'. Our hosting packages come with generous monthly data transfer allowances, see the Hosting Packages page for details. Data transfer can be monitored day-to-day via the stats utility in your webmaster control panel (cPanel). All services contribute towards the monthly data transfer usage: all website traffic, email sending / receiving / downloading, FTP uploads and downloads.
(Strictly-speaking the term 'bandwidth' actually refers to the rate at which data can be transferred to and from the server. All of our servers have 100 mbps (megabit per second) port connections to the internet with no throttling applied. This ensures responsive data transfer).