You will find many web hosts use the terms bandwidth and data transfer interchangeably, which can be confusing. Simply put, bandwidth is a rate; data transfer is a total. Bandwidth is measured in bytes per second; data transfer is measured in bytes per month. A web hosting plan is usually based on the amount of data you can transfer to and from the host’s servers in one month. The host’s bandwidth dictates how much of that data can be transferred in one second.
Try to picture bandwidth as a highway, with data as the cars, or traffic, on that highway. A larger highway has the capacity for more cars, resulting in a smoother flow of traffic. A web host with high bandwidth can transfer more data per second, so your website will load faster.
Many hosts claim to offer unlimited bandwidth or unlimited data transfer. Just as no highway can be infinitely wide, no web host can really offer unlimited bandwidth. What they are really saying is ‘we are pretty sure we have more bandwidth than you’ll need.’ If a host is offering unlimited bandwidth, make sure to read the fine print. Everything has limits!