Store Timezone kept in a file?

[Airheadbit]

While trouble shooting: Notice: date_default_timezone_set(): Timezone ID 'EDT' is invalid in /home/jthardwa/u-boltsrus.com/bagisto/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap/LoadConfiguration.php on line 49
it appears the time zone information for the store is stored in a file, somewhere..
Why?

[Vaishali Agarwal]

@Airheadbit
go to the .env file and check for the APP_TIMEZONE which should be valid.