The crampon attaches to the
mountain boot.
It is a many spiked device. These spikes
find purchase in the ice, just by being so sharp.
Often modern crampons will have large spikes
protruding forwards. When
climbing
a vertical face of ice
one kicks ones foot into the ice. These front points
grip the ice and one stands up on them.
This is referred to as front-pointing.
Before front-pointing was developed people had to
manually cut steps into the
ice.
I heard of some guy climbing in the Alps.
He mantleshelfed onto a ledge, but stood on his hands
with his crampons. I think he promptly fell
off and had to be air-lifted out of the mountain