Why is it free????

I am new to this forum …and a fairly recent pc user as well.I am sure that this question has been asked many times …please excuse my ignorance…but why do companies such as comodo offer this free use of their product?.I also use avg free …adaware free …etc.Could anyone out there please help me with this question.

Welcome to the forum . If you would go to the Talk to the CEO forum, Melih, has explained it very well.
He is the CEO of Comodo.