Why use "? Ver = 2.70" in the css or script route?

Question

Why do some people write this:

shop/js/uds-jsonp.js?ver=2.70 

instead

 shop/js/uds-jsonp.js 

I checked the resource with ?ver=2.70 or without ?ver=2.70 , and I did not see the differences.

Answer 1

This is for iterating over the cache if you change the version ( ver URI parameter) when the user loads the uds-jsonp.js , it reloads, and does not load from the cache, providing the latest version.