Automatic knives, also known as switchblades, are folding knives with a locking mechanism that allows them to be opened and closed automatically by pressing a button or lever on the handle. They are typically made of metal such as steel or titanium, and come in various sizes and shapes. Automatic knives are legal in some states and countries, while other places have restrictions or ban them entirely.

Butterfly knives, also known as balisongs or fan knives, are folding pocket knives with two handles that pivot around each other. They get their name from the shape of the handle, which resembles a butterfly's wings when opened. Butterfly knives are often used for everyday tasks such as opening packages and cutting rope, but they can also be used for self-defense due to their concealability and ability to be quickly deployed.

Fixed blade knives are knives with a non-movable blade, typically made of steel and designed to be used as a tool or weapon. They are often larger than folding knives and can range from small pocketknives to large hunting knives. Fixed blade knives are popular for their strength, durability, and reliability.

Folding knives are knives with blades that can be folded into the handle, making them compact and portable. They are also known as pocketknives or switchblades. Folding knives come in many shapes and sizes, from small pocket-sized models to larger fixed blade designs.

Specialty knives are designed for specific tasks and activities, such as hunting, fishing, camping, hiking, tactical operations, self-defense, and culinary uses. They usually feature unique designs and materials that make them more effective at their intended purpose than regular kitchen or pocketknives. Examples of specialty knives include machetes, axes, tomahawks, swords, daggers, folding knives, and multi-tools.