How can PHP handle login sessions between different subdomains of a website?

When handling login sessions between different subdomains of a website in PHP, you can set the session cookie domain to the root domain so that it is accessible across all subdomains. This can be achieved by setting the session.cookie_domain configuration in the php.ini file or using the session_set_cookie_params function in your PHP code.

// Set the session cookie domain to the root domain
ini_set('session.cookie_domain', '.yourdomain.com');

// Start the session
session_start();