ActiveX controls are small apps that allow websites to provide content such as videos and games. They also let you interact with content like toolbars and stock tickers when you browse the web. However, these apps can sometimes malfunction, or give you content that you don't want. In some cases, these apps might be used to collect info from your PC, damage info on your PC, install software on your PC without your agreement, or let someone else control your PC remotely.