common
	config/				contains shared configurations
	mail/				contains view files for e-mails
	models/				contains model classes used in both backend and frontend
	tests/				contains various tests for objects that are common among applications
    ext/                contains yii2 framework overrided classes
    mod/                contains application modules.
console
	config/				contains console configurations
	controllers/		contains console controllers (commands)
	migrations/			contains database migrations
	models/				contains console-specific model classes
	runtime/			contains files generated during runtime
	tests/				contains various tests for the console application
backend
	assets/				contains application assets such as JavaScript and CSS
	config/				contains backend configurations
	controllers/		contains Web controller classes
	models/				contains backend-specific model classes
	runtime/			contains files generated during runtime
	tests/				contains various tests for the backend application
	views/				contains view files for the Web application
	web/				contains the entry script and Web resources
frontend
	assets/				contains application assets such as JavaScript and CSS
	config/				contains frontend configurations
	controllers/		contains Web controller classes
	models/				contains frontend-specific model classes
	runtime/			contains files generated during runtime
	tests/				contains various tests for the frontend application
	views/				contains view files for the Web application
	web/				contains the entry script and Web resources
src
    ext/                contains yii2 framework overrided classes
    mod/                contains application modules.
vendor/					contains dependent 3rd-party packages
environments/			contains environment-based overrides