The following is everything you ever wanted to know about the ubiquitous little power adapter.Why do we need power adapters?
The simple answer is the design of our smaller digital devices today have a much lower power need than what is supplied by the Electric Company plug in your wall. Your power adapter simply takes that electricity and "transforms" it to the exact amount of electrical current the Manufacturer designed the item to use.
Why so many different kinds?
Now comes the tricky part where you need to pay attention. The reasons there are so many different kinds is 1) they all produce different electrical current as output, and 2) they have a different connection to the device.
How do I know which one?
Google is an excellent way to find your adapter as well as the original Manufacturer of your device (Dell, HP, Lenovo ...) If you have the original adapter then you look on the printed side. On there you will find its part number. Google that and you hopefully find a Company as eager as WIDGETREE to get you the right part at a great price!
In Summary ... it is very important that when you are replacing an adapter for one of your devices that you choose the correct one. An incorrect voltage or inferior (non OEM) can permanently damage your device beyond repair.