In WordPress, ob_start() and ob_get_clean() are used to control output buffering.
ob_start() is a PHP function that turns on output buffering. This means that any content generated by PHP will not be sent to the browser immediately, but will be stored in an internal buffer. This can be useful in many situations, such as when you need to modify or manipulate the output before it is sent to the browser.
ob_get_clean() is another PHP function that gets the contents of the output buffer and turns off output buffering. It returns the buffered content and deletes the buffer. This function is often used in conjunction with ob_start() to capture and manipulate the output.
In WordPress, ob_start() and ob_get_clean() are commonly used in plugin and theme development to modify the output of WordPress functions and filters. For example, you can use ob_start() to capture the output of a shortcode, modify it, and then use ob_get_clean() to return the modified output. This technique can be used to add custom functionality to WordPress without modifying the core code.
Overall, ob_start() and ob_get_clean() are powerful PHP functions that can be used to manipulate and modify output in WordPress, and are essential tools for developers who want to customize the behavior of WordPress.