Browsers may cache the webpages we visited, when user types a URL on the address bar, the browser may cache the webpage returned from server while displaying it. If there is no update on the webpage, then next time when the browser requests the same page, it will not download the page again, instead it will load the cached page. If the website explicitly specify that the page is updated, then the browser will download the page again from the server.What's HTTP Cache?You may be familiar with the cache mechanism of web browser. For example, the RSS subscribe page for JavaEye is http://www.iteye....

I’ve been on a web tweaking kick lately: how to speed up your javascript, gzip files with your server, and now how to set up caching. But the reason is simple: site performance is a feature.For web sites, speed may be feature #1. Users hate waiting, we get frustrated by buffering videos and pages that pop together as images slowly load. It’s a jarring (aka bad) user experience. Time invested in site optimization is well worth it, so let’s dive in.What is Caching?Caching is a great example of the ubiquitous time-space tradeoff in programming. You can save time by using sp...