Caching is a method of speeding up web page access. It works by making copies of recently accessed web pages and images and storing them locally on your computer or network. Therefore when you access that site again you are accessing a cached local copy of the site and not having to wait for it to download again which makes it quicker to access and reduces network traffic.
The disadvantage of caching is that you may need to refresh the site to retrieve any new updates on the website. Also, caches may hold unwanted scripts and files such as spyware and adware.
Next: Client-side Caching