A switchblade knife, popularly known as a flick knife or automatic knife is one in which the blade rests inside the handle. The blade has a release mechanism pressing which can open the blade. Have a look at the different types of automatic knives:

Side-opening (folding) knives:

The side-opening switchblade knife has an opening mechanism almost similar to that of regular folding knives with the blade pivoting from one side of the handle.

Out-of the-front switchblades:

In the out-of-the-front (OTF) switchblade knives, the blade comes out from the tip of the handle rather than the side. Although side-opening and OTF knives have a similar internal mechanism, one area where they differ is that an OTF knife blade can be sharp on both the sides.

Single action OTF:

Single action OTF Automatic Knives do not allow the blade to retract on the press of a button. You have to manually compress the spring to retract the blade. They have stronger springs and therefore the blades open more vigorously than double action OTF switchblades.

Double action OTF:

In a double action OTF switchblade, the blade expands when a button on the handle is pressed. Pushing the button also retracts the blade. When the button is pressed, spring tension occurs that moves the blade back to its position. As they are unlikely to open accidentally, these knives are safer to carry than their single action counterparts.