Plugin powers videos, animations and games you play inside the browsers. For example if you want to watch video on YouTube then you should install flash plug-in by visiting Adobe site. Similarly there are plugin to play Divx videos, Windows media videos etc.
You should update plugin time to time because not not every plug-in update by itself in the browser (The exception is flash plug-in which updated itself in the Chrome browser). If you use old plugin then your computer might be vulnerable to attack by malware, viruses and other security threats. Also plugins can save your time by giving you uninterrupted browsing experience.
Mozilla Plugin check
Mozilla made a nice “Plugin Check” page which tells you about all the plugins of your Firefox browser. It tells you which plugin requires update and which is up-to-date. If it needs any update then a download link of plugin page is provided by this tool.
In the screenshot above, you can see that Silverlight Plug-in needs update as the yellow button is flashed next to it on which “Update” is written. Similarly DivX player and Java are up to date because green “Up to Date” button is displayed next to it.
Click on the Update button to quickly update the vulnerable plugin. You’ll be instantly redirected to the manufacturer of the plugin page. While you click on the update button, you’ll be redirected to the manufacturer’s website on the same tab which is annoying. The new page should open in the new tab.