Adwares are programs that show advertisements when you use them. Some paid software offer a free option with ads. Most of the legit software removes those advertisements if you pay for that software. They are usually not harmful to users. But, There is also malware that installs these programs without your permission. One time I was trying to install some software and it installed some extension that showed ads on the browser. If you want to remove that adware, remove the software that came from. If you don't know which is that software, just restore windows to a recent restore point using Backup and Restore. If the adware is integrated into Mozilla Firefox, there most probably be a separate installation for the adware. Check Program and Features for any unusual software and uninstall them. In case you install the program it will install again by itself. To avoid this go to Start up a folder in Windows and delete any unwanted start-up items. To open the start-up folder, search on ...