How to make Device Drivers

I've started to learn Device Drivers, so this is just for memo.
It's just that there are easy explanations for device drives at the below URL.

http://www.opensourceforu.com/2010/11/understanding-linux-device-drivers/

The below URL indicates that what is Dynamically Loading Drivers. Besides, it includes how to write drivers.

http://www.opensourceforu.com/2010/12/writing-your-first-linux-driver/