A lot of people lease dedicated servers because of the fact that dedicated servers are expensive, but they need them to host their high bandwidth or high pc requirements on something that can take it. As you get to more expensive servers they will say something like "unmetered bandwith - 10 Mbit port" and then you say "Yes, a 10 Mbit port" and you think you have this HUGE amount of bandwidth... well sorry your wrong. Thats only about ~ 337GB/Month bandwidth, which, depending on your needs, could be very very small! I created a tool in which you input the speed of your port and it will tell you your monthly allowance of bandwidth. It could be quite useful! Check it out here