Why do we clear cache and cookies in a browser?

What are Browser Cache and Cookies and why should they be deleted regularly?

Explanation:
Any website you visit is actually a composition of  hundreds or even thousands of files. Even websites which are highly optimized for speed  are likely to load a lot of files at any point to display the content in your browser.

Browsers try to do their part to speed up the loading process. The first time you visit a site, the browser will save pieces of the site, because the browser can display the files stored in its cache much faster than it can pull fresh files from a server. The next time you visit that site, the cached files will help cut down the page load time.

Why should we remove those saved files (Cache and Cookies) though they are helpful in faster loading of the web pages?

Many times web developers have to make updates to the files that comprise your site in order to push a change or new feature live. If we change a file that your browser has cached, it’s going to keep serving the old, cached version of the file and you won’t see our most recent changes. This is when, you may encounter browser errors like run time error, buttons missing on the page, unable to save the Timesheet, Timesheet doesn't allow you to enter time, the action performed doesn't respond appropriately etc.

Clearing the Cache and Cookies in a browser helps fix these issues.