External keyboards come in a variety of forms, each with its own unique set of features and advantages. Some examples of different forms of external keyboards include:

1. Standard external keyboard: This is the most common type of external keyboard and it usually has a similar layout to the keyboard on a desktop computer. It typically has a full-size QWERTY layout with a numeric keypad, function keys, and a set of multimedia keys for controlling music and video playback.
2. Ergonomic keyboard: This type of external keyboard is designed to reduce strain on the hands and wrists during long periods of typing. It often features a split layout that angles the keys inwards to promote a more natural typing position. Some ergonomic keyboard even split the keyboard in half allowing to have your arm in a more natural position.
3. Gaming keyboard: This type of external keyboard is designed specifically for use with computer games. It typically has programmable keys, customizable lighting, and advanced macro functions that allow players to set up complex in-game commands. Some gaming keyboard also have anti-ghosting technology and mechanical switches.
4. Compact external keyboard: This type of keyboard is smaller in size and is ideal for use with laptops or tablet computers. It typically has a reduced layout with smaller keys, and may not have a numeric keypad.
5. Bluetooth keyboard: This type of external keyboard uses Bluetooth wireless technology to connect to a computer or other device. It can be used with a wide range of devices and eliminates the need for a USB cable. Some Bluetooth keyboard are also foldable and can be easily carried around.
6. Flexible keyboard: This type of external keyboard is made of a flexible material that allows it to be rolled or folded for easy transport. It’s useful for people who travel frequently or need to carry it around frequently.

Overall, external keyboards come in many forms, and the type you choose will depend on your specific needs and preferences. There are options for people who are looking for a portable keyboard, for people who want to gaming or people who want to type for long period of time with ergonomic design, or for people who need specific functionalities as a programmable keys.