A fast loading web page is an important factor that heavily weighs into a userís experience on your web site. And itís not just your audience taking notice of how quickly a page loads into their browser, Google uses this metric as part of their PageRank algorithm. Web designers and developers who are creating web sites will want to take this into consideration, and usually do by optimizing image filesizes, using semantic HTML and CSS, and controlling the amount of content that appears on any given page. However, web designers and developers can decrease their page load times even more by forcing the browser to cache specific types of content via the Expires header. In fact, both Google and Yahoo recommend implementing browser caching by setting the Expires header.