What is advantage of Elastic IP using with AWS lamp app?

Hello,
Looking at some AWS manuals I see Elastic IP using descriptions and adding new Elastic IP
and applying it to existing instance ip of my hosting was changed and ssh command
line was changed too, as I enter into AWS console with command like

ssh -i /path/myaws.pem ubuntu@ec2-NN-NNN-NNN-NNN.eu-central-1.compute.amazonaws.com

But what I missed what is advantage of Elastic IP using?
Now my php/laravel/mysql project is at dev stage.
The production version of my site would be hosted at https://www.cloudns.net/ account/domain.

but I found AWS/Route 53 and maybe I will use it for production of my siteā€¦

Thanks!