The photo above shows the four post-harvest states of an almond. From left to right, the almond with intact hull; the hull peeled back to reveal the shell; after hulling; and finally hulled and shelled nut.

Almonds are related to apricots—the botanical name for the almond is Prunus amygdalus; apricot is Prunus armeniaca. If you have ever cracked open an apricot pit to find a little almond-shaped object, you know about the similarity (indeed, the “apricot nut” has an almond-like flavor). We like the outer part of the apricot, but the inner kernel of the almond (note that green almonds, which can be eaten whole will occasionally appear in markets or restaurants in the spring).
Most almonds are harvested using specialized shaking machines that grasp the trunk of the tree, shake it, thus causing almonds to fall to the ground. An exceptionally flawed video at You Tube somewhat shows a machine in action.

The almonds sit on the ground for a little while and then are picked up by another specialized machine (something like a street sweeper). They are then transported to a processing facility—a facility which is typically not owned by the farmer—where they are cleaned and allowed to dry. After a time, the hull and shell are removed. These two items have value: the hull (or almond “fruit”) is sold to dairy farms as cattle feed while the shell is burned to make electricity or steam (a type of “bioenergy”). The hulled, shelled nuts are then returned to the farmer or sent to a processing facility to be roasted, ground, or packed for sale.