Good reference for learning PHPDoc?

There are two draft PSRs:
https://github.com/php-fig/fig-standards.../phpdoc.md
https://github.com/php-fig/fig-standards...oc-tags.md

From https://www.php-fig.org/psr/#draft

Why should we use it, where should it be used

Specifying Types is a good practice. It helps developers to understand code, reduce bugs, and helps static analysis or IDE.

In the old age, there is no type declaration in PHP:
https://www.php.net/manual/en/language.t...ations.php

So people used Doc comment, showing types as special comments.
@var, @param, @return, ...

Now PHP has type declaration, but not all the Doc comments cannot be specified as type declarations.
For example, if you don't use PHP 8.0 or later, you can't use Union Types:
https://www.php.net/manual/en/language.t...site.union

So when we can't specify types with type declaration, we still use PHPDoc.

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