Comment 11 for bug 1442851

> Using a "Restore previous session at startup" setting for
> "throwaway sessions" is awkward in several ways: it's not at all
> obvious that that's what it's for; either it doesn't clear your
> history+cookies, therefore satisfying only part of the use case, or
> it's not obvious that it does clear them; it doesn't let you have
> throwaway tabs and persistent tabs open at the same time; and having it
> as a setting is optimized for people who always or never use the
> browser that way, and not for people who *sometimes* use the browser
> that way. All those issues could be resolved by replacing it with a
> private/incognito area with its own set of tabs, cookies, and history
> that expires when you close its last tab. But that's a matter for
> another bug report.

The original use case for this setting is that of people who don’t want their open tabs to be remembered at the end of a browsing session (i.e. when they explicitly close the browser). It’s an entirely different use case from the private/incognito browsing mode (which by the way was just implemented). In private mode, as you point out, nothing is recorded (pages you visit are not recorded in the history database and data is not cached on disk), whereas that setting only discards the list of open tabs. Admittedly, this setting could be made more explicit, and in fact it is not part of the design spec (but was requested by a number of very vocal users). It can definitely be improved (or removed if it’s deemed unnecessary, but beware that the vocal users won’t let it go by without complaining!).