What is the significance of Passive Mode in FTP operations in PHP?

When dealing with FTP operations in PHP, Passive Mode is significant because it allows the client to initiate the data connection to the server. This is particularly useful when the client is behind a firewall or NAT router. To enable Passive Mode in FTP operations in PHP, you need to use the `ftp_pasv()` function to switch the connection mode.

// Connect to FTP server
$ftp = ftp_connect('ftp.example.com');

// Login to FTP server
ftp_login($ftp, 'username', 'password');

// Enable Passive Mode
ftp_pasv($ftp, true);

// Perform FTP operations in Passive Mode
// ...

// Close FTP connection
ftp_close($ftp);