Good cookies are usually used to: - remember your language/country, - store a temporary authentication token (when logging into a website, checking the "Remem

Good cookies are usually used to: - remember your language/country, - store a temporary authentication token (when logging into a website, checking the "Remember me" checkbox) so you don't need to re-login every day, - remember your name after you filled a commenting form on a blog post so the next time you comment it's already there - etc. Bad cookies are used to track you across different websites so they can target advertisements to what you have searched on Google or what pages you have visited. If you are concerned about your privacy you should use an extension such as Ghostery to block trackers and other bad cookies and then, as trebor says, accept all the other ones coming from 1st party sites since they usually want to help you