What is the difference between Yii::$app and \Yii::$app?

Question

Yii

What role does the slash play? From time to time I meet different spellings, but I did not find the answer in the documentation.

Answer 1

Yii::$app - used when the namespace is included via use;
\Yii::$app - used when the namespace is included directly in the code. Actually, the slash before Yii indicates that in order to include this namespace, you need to go beyond the current one.

Answer 2

php.net/manual/en/language.namespaces.global.php