Internet Explorer, though no longer a widely recommended browser, has had several key features. It provided a user-friendly interface with a familiar layout, including a toolbar for easy navigation. Internet Explorer historically supported ActiveX controls, enabling interactive web content and browser extensions. It offered robust security measures like SmartScreen Filter to identify malicious websites and pop-up blockers to enhance user experience. Additionally, it allowed users to customize their browsing experience with add-ons and toolbars.