Avira

Is Avira AntiVirus completely free and good?

Also, is it trusted?

Do you know any other Anitvirus?

I have never heard of that AntiVirus system.
You should use Mcafee or Norton.

I use Avira. It is the best on the planet if you google it. No, it is not free, obviously. It beat Kaspersky and many others in tests and has the most effective firewall combined with a powerful hardware firewall.