Compression is an important technique for improving performance. It is the use of an algorithm to remove redundancy in a file in order to make it smaller. This improves transfer speed and bandwidth utilization.
Software developers do not need to programmatically compress data that is to be transmitted. Servers and browsers have compression implemented already. As long as both the server and the browser understand the compression algorithm, it can be used. It is just a matter of ensuring that the server is configured properly.
The two main types of compression that are used to improve web performance are file compression and content-encoding (end-to-end) compression.