Hi Susan, Usually, Firefox keeps an amount of pages instead of days. The amount depends on performance. It allows you to store a max amount of pages as long as that number doesn't affect your user experience. You can check the amount of pages by opening a new tab and going to "about:config" on you address bar. A page should open with a search bar, then type "places.history.expiration.transient_current_max_pages", you should see the number of pages Firefox can hold at that particular session! I hope that helps! Best,