Browser caching is a process by which copies of the page or other web resources are stored by the browser to return them to the viewer quickly, reducing the loading speed of the website. It works in a way that the request does not reach the server directly. Instead, the viewer request is analysed by the browser, and if it has cached copies of the webpage, it will return those and would not bother the server at all.
Normally, this is an ideal and fantastic way to reduce your browsing lags and theoretically, you could store cached copies of all websites and use them instead. So, why not?
Well, firstly, because storing these entire copies of millions of websites in a browser is impossible. Even if it was possible, cached copies ensure that you can see the content that is lighter to load. So, secondly, using this idea to view entire websites is a practical failure because of its inability to show the entire website, with ALL its elements.
That said, cached copies of websites help in plenty of scenarios, especially related to search engine optimization. The SEO company needs to follow certain laid-down policies to restrict their use of caching to provide an optimum user experience. This is called Cache Control.
Cache control has various directives to channelize and regulate this browser function and are usually listed in the following format:
Key: Header Value
E.g. cache-control: no cache
Here’s a brief explanation of various cache control headers.
- cache-control: no cache
A no cache directive is used to honour the authenticity of the webpage and its maker’s content. It takes the browser to the server directly, for authentication purposes. It requires a confirmation from the parent server before it can use the cached copy of the webpage.
- cache-control: no transform
In order to save space or increase the loading speed, the cached copy is sometimes tweaked by the browser in means of elements of content or graphics. The no transform directive gives an explicit instruction that the content of the cached copy should remain identical to the website or webpage.
- cache-control: max age
Max age, as a directive, helps in establishing a duration for the cached response to be used by the browser. It is specified in seconds and it clearly states how long an HTTPS response should remain in a browser before it can be reused.
- cache-control: s-maxage
It is similar to the max age directive but differs in a way that it mainly relates to the Content Delivery Network (CDN) and overrides the max age directive in certain situations.
- cache-control: no store
The no store directive is similar to the no cache directive and requires a new HTTPS request every time. The entire response has to be downloaded from the parent server at each request. This directive is mainly used in keeping crucial information like banking details safe and private.
Using a Content Delivery Network (CDN) for cache control: CDN makes use of secondary local servers to save cached copies of the websites and webpages, an efficient technique in optimization of web loading speed. It has manifold benefits like simplification of the caching policies, segregating static cached pages and automated caching from the viewer’s end.