What's this kind of syntax in PHP?

Question

$test= <<

I have never see it before. What\'s it used for?

Answer 1

Indeed, this is the Heredoc syntax.

Just in case you are wondering what interest it can have vs the regular string delimiters:

// These strings contain the same thing '"'"
$s1 = '\'"\'"';
$s2 = "'\"'\"";
$s3 = <<

No more quote escaping.
A typical use case for me is when I need to store in a string some HTML code I have copy/pasted.