Network data compression
Data compression involves encoding information using fewer bits than the original representation. Compression can be either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. The process of reducing the size of a data file is often referred to as data compression. 
A good INTRODUCTORY video to help you understand this
The video below is used with gratitude from code.org
a much better video to help you understand it
This video below is used with gratitude from computerphile 
Compression has enabled information to be disseminated more rapidly.
Why compression of data is often necessary when transmitting across a networka group or system of interconnected people or things.
Because networksa group or system of interconnected people or things. are sensitive to congestion, and networka group or system of interconnected people or things. availability is often expensive. The key reason is because compressed data can be transmitted and received much faster than non-compressed data.
These standards are used from the IB Computer Science Subject Guide
- ExplainGive a detailed account including reasons or causes. why compression of data is often necessary when transmitting across a networka group or system of interconnected people or things..
- IB Diploma Programme Computer science guide (first examinations 2014). Cardiff, Wales, United Kingdom: International Baccalaureate Organization. January 2012.