<span class="application">[Tor Browser](https://www.torproject.org)</span> 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/Tor Browser</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.
You can change the security level of <span class="application">Tor Browser</span> 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…**.