Quality of service is another important reason to consider web caching.
The time it takes to receive a document from the web plays a very important role in how enjoyable the users web browsing experience is. It is often said that a response time over two seconds is too long for most users. Unfortunately, response times over two seconds are very common on the web. Even on networks where local internet bandwidth is not saturated and does not impose any limits on the speed of the clients browsing, the internet at large is out of the control of local network administrators. There will be temporary network slowdowns, distant web sites will sometimes be overloaded, and web pages will occasionally be large and slow to load.