If this is the first article you read about Cache, congratulations, you are lucky you find this simple and straightforward information about it, more specifically about Web caching.
Cache can be implemented by Software or Hardware, it doesn’t matter, it is an optimized storage for delivering fast content between you PC and the Internet content you are browsing.
When you visit your favorite page, most of the content is not coming from the server, it is coming from the cache, because the cache is already stored from the remote server the first time you visit the page.
If the page loads from the server every time you visit your page, it will cause bottlenecks somewhere in the “road”, especially if the page is visited at the same time by many people. This is why it is more likely you will have the impression that your favorite page loads faster. Nobody likes slow websites, and this is why cache is necessary.
During every connection between a device and a server more than one cache can be used during the connectivity, even your browser implements a cache, sometimes called proxy.
But how does a basic cache work? Assuming the most basic scenario, a cache might works as follows:
When you visit a page for the first time, the response time will always be the slowest one, because the response is being served directly by the server; however a copy of the response data is stored in the cache.
After the first time the page is visited the client request will be served primarily from the cache. If there is data needed to be updated it will be brought directly from the server and a copy of it will be stored in cache. This approach will provide a faster response and reduce server traffic.
However, you might be asking yourself some questions: how does the cache determine when to refresh a specific content? How to assure that the data display is always the most accurate data?
The above is being determined by cache policies; that are basically rules-algorithms that manage a cache; usually being a combination of several rules as for example: last written time, last access time, less access data, etc. Only the browser itself utilices a combination of very complex policies, aiming to provide faster page loads.
As a general conclusion, it can be assumed that your devices accessing and requesting info from the Internet utilize a cache mechanism. Most of the time you don’t need to take it, it is being implemented out of the box; however in some complex scenarios this cache implementation and/or policies would require to be adjusted in order to provide a better customer experience; being this task more complex every day since technology trends are evolving constantly.