Their are 2 names for an IMEI number IMEI or MEID but we use IMEI.
At some time you may be asked for information about your phone as you IMEI number this is a unique number for your device, no 2 devices will have the same imei number. This makes devices like iphones and samsung phones more secure as they are more easily tracked if they are lost. It also makes it harder for people to make copies of phones as their are websites that allow you to check the IMEI number.
Finding your IMEI number is quite simple and easy to find.
You simply need to dial *#06# and the IMEI number should just appear without pressing the call button.
On some iphone like the iphone 5, 5C, 5S you can find your IMEI number on the back of the iphone. We would say not to trust this number as the housing of a phone can be changed making this information incorrect.