Cookies, in the computer lingo, are small data files stored by various websites on your computer as you browse them through your web browser. Cookies are stored for all web browsers like Internet Explorer, Chrome, Firefox etc. Some of the cookies are useful as they store your login data for websites like Gmail, Yahoo!, Outlook etc., so that you do not have to login over and over again. On the other hand, some other cookies are not so useful and just use up your browser’s storage space. If you are a Firefox user, then you can selectively remove only the cookies from websites that you want and keep the cookies from other websites, using the Biscuit extension.
You can download and install Biscuit extension for Firefox from the Mozilla add-ons repository. After the installation, you would find a new item under the Tools in the menubar. If you are not able to see the menubar in Firefox, then press the Alt key once and it would appear. You can open the Tools → Show Cookies from the menubar to view the Biscuit interface for deleting or preserving cookies from different domains.
Here you can find a website for which you want to keep the cookies. All the cookies stored in your web browser for a domain are given under that domain name. To preserve that cookie, right-click on it and select Check from the context-menu. If you want to remove the unwanted cookies then you can click on the Remove All Cookies button.
If you want to delete all the cookies (even those that you have set to be preserved), then you can disable cookie preservation by clicking on the small X button next to the Remove All Cookies button. Now if you delete all the cookies through the Remove All Cookies button, then all the cookies shall be deleted, irrespective of their preservation status.
In the options for Biscuit extension, you can choose to hide the extension from the menubar, remove unwanted cookies at Firefox shutdown and customize the cookies dialog in various ways. There are also options to export or import the cookies preservation settings.
The Biscuit extension gives Firefox users an easy to use and very effective cookie manager that should have been a part of Firefox in first place. The Biscuit cookie manager for Firefox can help you selectively remove all the unwanted cookies and save only a few cookies that really matter for you.
You can download and install the Biscuit extension from
https://addons.mozilla.org/en-US/firefox/addon/biscuit-220876/. (In October 2018, Mozilla removed all classic add-ons but you can install it through Classic Add-ons Archive as explained in https://www.trishtech.com/2018/10/use-older-firefox-extensions-through-classic-add-ons-archive/).