How do soap dispensers that put out foam work?

Question

There are some soap dispensers that when you pump out the soap, foam comes out and you do not need to rub your hands to create the foam. How do these work???

Answer 1

When the soap is in the container, it has no contact with air, so, it stays in its "gooy" or soapy form. For it to surn into foam it has to come into contact with air. In other words when you squirt it onto your hands it's touched air and becomes foamy.

Answer 2

usually it is heat generated