What are some best practices to follow to prevent the "headers already sent" error when using the header() function in PHP?

When using the header() function in PHP, it is important to ensure that no output is sent to the browser before calling this function. To prevent the "headers already sent" error, you should make sure that there is no whitespace or HTML tags before the opening <?php tag in your PHP file. Additionally, you can use output buffering to capture any output before sending headers.

&lt;?php
ob_start(); // Start output buffering

// Your PHP code here

ob_end_flush(); // Flush the output buffer