add filter in wordpress

function custom_filter_function( $content ) {
    // Add your custom filter logic here
    return $content;
}
add_filter( 'the_content', 'custom_filter_function' );

Step 1: Create a new function named "custom_filter_function" which takes the parameter "$content". Step 2: Inside the function, add your custom filter logic. Step 3: Return the modified content. Step 4: Use the "add_filter" function to add your custom filter to the desired WordPress hook, in this case "the_content".