Hi

Yes you can use Firefox if you have Windows Defender installed in Windows 10. Always a good idea to have anti-malware software installed to protect your device and data.

I had read online that Windows Defender is only effective in providing its security functions only if you are using Microsoft EDGE. I guess my question should have been is Defender fully functional regardless of the browser used?

Windows Defender is basically composed of 3 items :

- Antivirus : It will scan files downloaded by whatever browser you are using.

- Firewall : It will block/allow network flows going outside/inside your computer, with no link to the browser used either.

- Web protection : has capability made up of Web threat protection and Web content filtering. Not to be confused with "Smartscreen" which is dedicated to Edge. Web protection generally use a plugin in browsers to be able to "read" data displayed by any browser. By default there is no supplier for web protection, so it's "disabled". So yes, with Smartscreen in Edge, there is additional protection : https://support.microsoft.com/en-us/help/17443/microsoft-edge-smartscreen-faq

I had read online that Windows Defender is only effective in providing its security functions only if you are using Microsoft EDGE. I guess my question should have been is Defender fully functional regardless of the browser used?

It should work in Firefox, you can check it by entering about:support in the URL bar, under the Security software section.