Bandwith definition

Ok guys if you can tell me this I'll be impressed.  In computing Bandwith referes to how much data can be moved.  High Bandwith connections allow for faster data transfer.  In electronics it refers to how many frequincies can pass through a filter.  It's computed by subtracting the lower freq. form the higher freq that can pass through the filter.  How is it calculated in computer networking or is it just used as slang and has no real hard meaning or definition.