title: How are zlib, gzip and zip related? What do they have in common and how are they different?
body: <p>The compression algorithm used in <em>zlib</em> is essentially the same as that in <em>gzip</em> and <em>zip</em>. What are <em>gzip</em> and <em>zip</em>? How are they different and how are they same?</p>