Your phone IMEI is its unique serial number you can use to identify your mobile (phone), unlike your phone number which can tied to your SIM car...
So sometimes its important to know your IMEI number, so how do you find it?
Step 1:Type this code into your phone *#06#
Step 2 :Now you should see a 15 digit number appea on your screen
For apple iPhone users the IEMI number is in your general phone options, see picture