What does the [L] flag signify in mod_rewrite rules in PHP and how should it be used?

The [L] flag in mod_rewrite rules signifies that if the current rule matches, no further rules should be processed. It stands for "last" and indicates that this is the last rule that should be applied in the current round of rewrite processing. It is important to use the [L] flag correctly to prevent unintended behavior in your rewrite rules.

RewriteEngine On
RewriteRule ^old-page$ new-page [L]