Transfer speed and connection speed

we always express connection speed in kilo bits per seconds and transfer speed in kilo Bytes per second.why is that so?

I am an oldtime bulletinboard sysop. Transfer speeds for downloads were a big deal when dialup connection speeds were slow. Files sizes are usually in bytes/kilo bytes so you can guess how long it will take by looking at the size and dividing.

I don't remember if we commonly used bytes when describing modem connection speeds. A 56k modem was connecting (in theory) at speeds upto 56,000 bits/second. Although 42k was more common (and still is).

When LAN's came along they did their connection speeds in bits not bytes. A reasonable conversion is 10 bits to the byte. This gives you an approximation of one into the other.

What I can't tell you is if that is some formal institutional thing that caused this.