How can the issue of "Cannot modify header information - headers already sent by" be resolved in PHP?

The issue of "Cannot modify header information - headers already sent by" occurs when PHP tries to send headers to the browser after it has already sent some content. To resolve this, make sure that there is no output (such as HTML, whitespace, or error messages) before calling functions like header() or setcookie(). To fix this, you can use output buffering to capture any output before sending headers.

ob_start(); // Start output buffering

// Your PHP code here

ob_end_flush(); // Flush the output buffer and send headers