When you browse the Internet, your computer and browser store certain pieces of information (in particular, images, logos and graphics), in a specific folder on your computer. This folder is called cache. The cache functions as a short-term memory for your browser.
Whenever you open a website you’ve visited before, your browser loads the files from the cache instead of downloading the whole website data again from the Internet. This makes using the Internet faster, especially for those websites you visit on a regular basis.