How can regular expressions (regex) be used in htaccess for URL redirection?

Regular expressions can be used in htaccess for URL redirection by matching specific patterns in the incoming URLs and redirecting them to a different location. This can be helpful for redirecting URLs with specific query parameters, patterns, or keywords to different pages on the website. ```apache RewriteEngine on RewriteRule ^old-page/(.*)$ /new-page/$1 [R=301,L] ``` In this example, any URL that starts with "old-page/" will be redirected to "new-page/". The $1 in the RewriteRule captures any additional characters after "old-page/" and appends them to the new URL. The [R=301,L] flag specifies a permanent redirect and stops further processing of rules.