Cache refers to a storage unit that stores certain data in a reserved memory and helps in making the system faster. When you work on the internet there also the browser cache the page you visit so that when you visit it again it opens up faster. The cache busting is related to that where a special code is used by the cache buster on a browser. The code prevents the browser from reading if the webpage has already been viewed by the user and has been cached in computer.
Using a cache buster on your browser doesn’t mean that you don’t get the file. Instead it just stops the browser from using that file from the cached memory. For this, a random number is inserted by the cache buster into the advertisement tag every time a page reloads on the user’s computer. This way the ad has a unique code and is not read by the cache memory. It is read as a new file by the cache memory. It is generally used by the publisher and allows him to show the advertiser that the ad has had more unique visitors than the actual number. It helps the publisher to get better inventory and is therefore popular with them.