(this guide focuses on Laravel's development server, Homestead)
For example; Homestead by default creates SSL certificates for your local websites, however you have to always click "Proceed/Trust/Make exception" or trust every website's certificate manually before being able to visit the site. By installing the Root CA (roughly: the certificate which is used to create the website certificates), you instantly trust all certificates that are derived from it.
Normally on an Nginx webserver (e.g. on Homestead) the certificates are stored in the /etc/nginx/ssl
folder. You see all the certificates that are generated for your local websites, including 3 crucial files:
ca.homestead.homestead.cnf
ca.homestead.homestead.crt