Today I have checked performance statistics of my website using YSlow. I got a warning (or error may be) which is as below
Add Expires headers
There are 15 static components without a far-future expiration date.
* (no expires) http://www.example.com/video/css/global.css
* (no expires) http://www.example.com/video/js/global.js
* (no expires) http://www.example.com/video/images/main-bg.png
What this means and how to achieve this in PHP and ASP.NET both. I am on shared hosting server, so please tell me some way to do this using code, because I'll not able to make any modification at the server end.
If I'll expire the header then is there any chance that if I'll make changes in the CSS then user will not get them right away because css and other files are cached for a certain time limit (1 month, week). Is it?
Is there any disadvantages of using expire headers??