Hello.

There are a few extensions that will let you manage your cookie permissions in an easy way. I recommend CS Lite.

There is a way to do this without add-ons, however. Go into Tools > Options > Privacy > Firefox will:Use custom settings for history and then untick Accept cookies from sites. You can then click Exceptions... to configure the extensions. It's very straightforward, but doing it with a cookie manager is easier. Alternatively, you can leave Accept cookies from sites ticked and set Keep until: to ask me every time. This may be easier to manage, for some users, but it will mean a lot of prompts, if you browse through a lot of different sites. I actually used this setting for a while and dealt with it quite well, until I got fed up and start using CS Lite (back then it was called CookieSafe). Ultimately, it's your choice.

I hope this helps.

The procedure for newer versions of Firefox (or perhaps different OS?) is very similar, though slightly different.

I am loathe to install addons that I don't need -- which for me is "when I can do whatever needs doing from Firefox itself."

Go into Edit -> Preferences and click on the Privacy image. Set the dropdown list to Use custom setting for history and untick Accept cookies from sites. Then click Exceptions and add any sites you /do/ want to allow to have cookies.

It's pretty much the same, you just get to the Privacy area differently.

Basically it is to let all cookies expire if you close Firefox and make an allow exception for sites that you want to keep cookies from.