Button inside form automatically acting as submit

Question

I had a button inside a form, with a number of inputs as well. The button was NOT designed to submit the form, but rather to activate some javascript. However, every time I clicked it while I was debugging, my console said that it was submitting. I moved the button out of the form, and the problem was solved. However, I am curious as to why the button automatically acted as a submit button. I did not give it any attributes except a class, and text between the open and close tags. There was no action, and the onClick called a separate JS function.Does anyone know why a button inside a form is automatically treated as a submit button?