Its simple.
The compression is due to the algorithms we perform on the file, mostly cryptographic algorithms. eg: run length encoding, more...
take a file with text inside, lots of words occur twice, thrice or lot of times. The repeated words are removed and their count and location are remembered(which takes less space than the words in separate). Later which decompressing, the words are restored.
You can also see the compression simply by doing the following.
1. Take a image file of size around 1-5mb.
2. Insert the image into MS Word.
3. Save the word file.
4. Now check the size of the word file. 😀 it will be less than the size of the image because, MS Word has a compression algorithm.
Like ways lots of algorithms are present for compression.
" The more we compress, the more time it takes to decompress "
Some useful links.
1. #-Link-Snipped-#
2. <a href="https://en.wikipedia.org/wiki/Data_compression#Applications" target="_blank" rel="nofollow noopener noreferrer">Data Compression Applications</a>
