What are some best practices for securing PHP files from unauthorized access?

Securing PHP files from unauthorized access is crucial to prevent sensitive information from being exposed. One best practice is to place PHP files containing sensitive information outside the web root directory, so they cannot be accessed directly through a URL. Another approach is to use .htaccess files to restrict access to specific directories or files based on IP addresses or passwords.

// Example of using .htaccess to restrict access to a directory
// Create a .htaccess file in the directory you want to protect
// Add the following code to the .htaccess file

deny from all