Some users choose to disable cookies in their web browsers. Such an action can reduce some privacy risks, but may severely limit or prevent the functionality of many websites. All significant web browsers have this disabling ability built-in, with no external program required. As an alternative, users may frequently delete any stored cookies. Some browsers (such as Mozilla Firefox and Opera) offer the option to clear cookies automatically whenever the user closes the browser. A third option involves allowing cookies in general, but preventing their abuse. There are also a host of wrapper applications that will redirect cookies and cache data to some other location. Concerns exist that the privacy benefits of deleting cookies have been over-stated.