Must-have Firefox add-ons for safer and trouble-free browsing

One of my favorite browsers is Mozilla Firefox, for several reasons, but mainly because it is quite safe and can be modified using add-ons to browse even more safely. These are some of my favorite plugins that give me a trouble-free browsing experience and protect me from malware, virusses and all sorts of web attacks :

• Noscript (Download) : This add-on disables all Javascript by default and protects you from Cross-site scripting (XSS) and other kind of web attacks. You can manually enable the Javascript of sites you trust and leave the Javascript of unknown sources disabled.
  
  A lot of websites use Javascript to enhance the browser experience. Some are small and innocent like loading a Flash-animation. While others use a vast array of scripts to make a fully dynamical website using AJAX, like Google, Facebook and Flikr.
  But unfortunately some Javascript has no good intentions and tries to install malware or steal personal information (usernames, passwords, credit card information, ...). Sometimes these bad scripts are added to websites you trust (because these websites were compromised), or you end up on a shady website by accident.
  Your browser executes all Javascript by default, even the bad Javascript. So if you visit a website that contains bad Javascript, it will be executed. Unless you turn Javascript off completely, but then websites like Facebook or Gmail won't work.
  Or you can install the Noscript add-on and take control of which Javascript is executed by your browser.


• Adblock Plus (Download) : This add-on removes all advertisements from the webpages you visit. It uses a list of advert-providing websites and blocks all images, scripts, iframes and pop-ups that originate from these sites. The list is maintained by the developers of Adblock Plus, so you don't have to do this yourself.
  Install this add-on if you want ad-free surfing.


• Flashblock (Download) : This add-on disables all flash-plugins on a website. By a simple mouse click, you can view them.
  
  Some website are flooded with flash-plugins and make it cumbersome and slow. This add-on disables them all, so they don't load.
  If you do want to see them, for instance to watch a YouTube clip or to play a flash game, you have the choice to enable it.