What changes when you open a private window
Incognito is Chrome’s name for a separate browsing session that limits information retained on your device. Firefox calls its equivalent a Private Window. The useful distinction is between records left in that browser and activity visible elsewhere. A private window can help when borrowing a computer or using a second account, but its name does not promise that the websites you contact lose their own records.
Closing one window may not end the session
Google says a Chrome Incognito session ends when all Incognito windows are closed. Cookies and site data used temporarily during that session are then removed. Mozilla likewise says Firefox removes the current session’s data when the last Private Window closes. For example, closing a shopping tab while another private window remains open is not the same event as ending the private session. Count the open private windows rather than assuming a closed tab finishes everything.
Downloads and bookmarks can remain
Google explicitly says downloaded files, saved bookmarks and reading-list items remain after Incognito ends. Mozilla also says downloaded files and bookmarks survive a Private Window session, even though those downloads do not appear in Firefox’s Downloads list. A saved PDF therefore needs to be considered separately from the page where you found it. If your goal is to avoid leaving a document on a shared computer, closing the browsing session does not answer whether that file is still in the Downloads folder.
Who may still observe your activity?
Google warns that websites and organisations managing a network, including schools, employers and internet providers, may still observe activity. Mozilla also states that private browsing does not hide your IP address or make you anonymous. The exact information available to a particular observer depends on the network and service; this guide does not claim that every observer can read every page’s contents. The point is narrower: a browser’s local-history setting is not evidence that the network connection has become invisible.
Signing in still identifies you to that service
Mozilla explains that when you sign into a website in a Private Window, the website knows which account you are using and can attach activity to it. A private browser session and a website account history are separate things. If you deliberately log into a shopping account, for instance, the absence of that visit from local browser history does not imply that an order disappears from the retailer’s account records.
Choose private browsing for the problem it addresses
For a separate temporary sign-in session, a private window can be useful. For a downloaded file, inspect where the file was saved. For activity attached to an account, check that service’s own records and controls. For a shared computer, finish by signing out where appropriate and closing every private window. These are different checks because they concern different places where information may remain. This is a general browser guide based on the linked vendor documentation, not a claim that we tested every browser version or workplace setup.