*[Tor Browser](https://www.torproject.org)* is a web browser based on [Mozilla Firefox](https://www.mozilla.org/firefox/) but configured to protect your privacy.
<p>To prevent Tails from running out of memory and crashing, download very big files to the <i>Persistent</i> folder. The files that you download outside of the Persistent Storage are stored in memory (RAM), which is more limited.</p>
Notice the padlock icon on the left of the address bar saying "mail.riseup.net".Notice also the address beginning with "https://" (instead of "http://"). These are the indicators that an encrypted connection using [[!wikipedia HTTPS]] is being used.
<p>To understand better the behavior of <i>Tor Browser</i>, for example, regarding JavaScript and cookies, you can refer to the <a href="https://2019.www.torproject.org/projects/torbrowser/design/"> <i>Tor Browser</i> design document</a>.</p>
You can change the security level of *Tor Browser* to disable browser features as a trade-off between security and usability.For example, you can set the security level to *Safest* to disable JavaScript completely.
To change the security level, click on the [[!img security-level.png class="symbolic" link="no"]] icon on the right of the address bar and choose **Settings…**.
<p>You can safely disregard the message, "Your browser is being managed by your organization," which appears in the <i>Tor Browser</i> preferences.</p>
<p>All this message means is that the automatic updates feature of <i>Tor Browser</i> has been disabled. This is done intentionally in Tails to make sure that no security feature or configuration gets broken by automatic updates of <i>Tor Browser</i>.</p>