It is very essential to back up your contact list so that even if you lose your phone or sim card or you decide to change your phone, you can easily get them back.
To do that you must have a working Gmail account but if you don’t have one then create a gmail account.

You will need to create a file to save all your phone contacts and get it ready for backup, Through your phone contacts. Read more... http://www.vertvision.org/2017/09/an-easy-way-of-backing-up-your-phone.html