Throughput
How much work or data a system can handle over a given stretch of time.
Glossary
Bandwidth
The maximum rate at which data can move along a given pathway.
In one line
The maximum rate at which data can move along a given pathway.
Also calledcapacitychannel capacity
Bandwidth is the width of the pipe. It sets an upper limit on how much information can travel through a channel in a given moment, no matter how eager either end may be. It is a ceiling, not a guarantee; actual flow can fall below it, but never rise above it.
A driver works within the bandwidth available to it, packing requests efficiently so that a limited channel is used as well as it can be. Wasting capacity means slower results, so careful drivers fill the pipe steadily without trying to push past its limit.
It helps to tell bandwidth and throughput apart. Bandwidth is the most a pathway could ever carry; throughput is how much it actually carries in practice. Overhead, waiting, and interruptions usually keep real throughput somewhat below the bandwidth ceiling.
When bandwidth is scarce, choices have to be made about what matters most. Important data may be given priority over less urgent traffic, so the limited capacity serves the things that need it first. Managing a narrow pipe well is often more valuable than simply wishing for a wider one.
In practice
In practice, bandwidth is like the number of lanes on a road. More lanes let more cars pass at once, but the lanes set a hard limit no amount of eagerness can exceed. A data channel works the same way: its bandwidth is the most it can ever carry in a moment.
