In what ways can the use of .htaccess files impact the functionality and security of a PHP website?

Using .htaccess files can impact the functionality and security of a PHP website by allowing for configuration settings that can restrict access to certain directories, redirect URLs, set custom error pages, and more. However, improper configuration of .htaccess files can also introduce security vulnerabilities if not set up correctly. To improve security, ensure that sensitive files are not accessible via the web and prevent directory listing by adding the following code to your .htaccess file: ```apache Options -Indexes <FilesMatch "\.(htaccess|htpasswd|ini|phps|fla|psd|log|sh)$"> Order allow,deny Deny from all </FilesMatch> ```