What does this rewrite rule mean? thanks-php Tutorial

What does this rewrite rule mean? Thank you for RewriteRule ^ () $ % {HTTP_HOST} $1 [C]. what does this mean? solution ------------------ rewrite & quot; to & quot; yourhostname.com & quot;, where % {HTTP_HOST} indicates the host name, and $1 indicates the rewrite rule that matches the first submode. what does this mean? Thank you.
RewriteRule ^ (/) $ % {HTTP_HOST} $1 [C]

What does this mean?

------ Solution --------------------
Rewrite "/" to "http://yourhostname.com/", where % {HTTP_HOST} represents the host name, $1 represents the string that the first sub-pattern matches, in this case it is. As for [C] said the rule and the next used, you can go to the Apache official website to find the relevant instructions: http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html#rewriterule