If you worry that your Tails might be corrupted, do a [[manual upgrade|doc/upgrade]] from a trusted operating system to upgrade it to a trusted version of Tails.
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<h2 id="javascript">Why is JavaScript enabled by default in <span class="application"i>Tor Browser</spani>?</h2>
Installing add-ons in *TorBrowser* might break the security built in Tails.
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<div class="next"> <ul> <li>[[Warnings about persistence|doc/first_steps/persistence/warnings#index3h1]]</li> <li>[[Browsing the web with Iceweasel<i>Tor Browser</i>|doc/anonymous_internet/Tor_browser]]</li> <li>[[Can I hide the fact that I am using Tails?|doc/about/fingerprint/]]</li> </ul> </div>
<h2 id="update-add-ons">Should I manually update add-ons included in <i>TorBrowser</i>?</h2>
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As explained in our documentation about [[the fingerprinting|doc/about/ of *Tor Browser* in Tails|doc/anonymous_internet/Tor_Browser#fingerprint]], Tails provides anonymity on the webby making it difficult to distinguish a particular user amongst all the users of Tails and the Tor Browser Bundle (TBB*Tor Browser* (either in Tails or on other operating systems).
As explained in our documentation about [[the fingerprint of *TorBrowser* in Tails|doc/anonymous_internet/Tor_Browser#fingerprint]], Tails provides anonymity by making it difficult to distinguish a particular user amongst all the users of *TorBrowser* (either in Tailsor on other operating systems).
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So, the information retrieved by such fingerprinting websites is not harmful for anonymity in itself, as long as it is the same for all Tor usersusers of *Tor Browser*.
So, the information retrieved by such fingerprinting websites is not harmful for anonymity in itself, as long as it is the same for all users of *TorBrowser*.
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For example, the user-agent property of the browser was set to `Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3`, as of Tails 0.21 and TBB 2.3.25-13. This value preserves your anonymity even if the operating system installed on the computer is Windows NT and you usually run Firefoxstring of *Tor Browser* includes <em>Windows NT</em> but this value preserves your anonymity even if you run Windows NT. On the other hand, changing this value makes you distinguishable from others Tor users and br users of *Tor Browser* and, as a consequence, weakens your anonymity.
For example, the user-agent string of *TorBrowser* includes <em>Windows NT</em> but this value preserves your anonymity even if you run Windows NT. On the other hand, changing this value makes you distinguishable from other users of *TorBrowser* and, as a consequence, weakens your anonymity.
No, as other Linux systems, Tails doesn't require an antivirus to protect itself from most malwares, such as viruses, trojans, and worms. There are various reasons why Linux operating systems generally don't need antivirus software, including the permission design of Linux systems.
