What is flash message
There exists a generic system to show users that an action was performed successfully, or more importantly, failed. This system is known as "flash messages".
What is yii2 flash?
Yii2 flash provide an easiest way to show flash message
INSTALL
Begin by pulling in the package through Composer
composer require wyno/yii2-flash "dev-master"
Usage
You may use helper to generate flash messages like this
flash()->success('Some message to notify');