Laravel offers us a great diversity possibilities out of box. Like as environments of production and development, and knowing about config is essential to start understanding how framework works.
It is often helpful to have different configuration values based on the environment where the application is running. For example, you may wish to use a different cache driver locally than you do on your production server.
By default the main configuration file is .env and it’s in main folder. How I told in a past post, Laravel uses the DotEnv Library to get these variables inside this file. The .env file is ignored by GIT because each environment can have a different configuration.