Why is information displayed on the screen without an output function?

Question

PHP

<?
$ch = curl_init();
$request_headers = array();
$request_headers[] = 'apikey:helloworld';
curl_setopt($ch, CURLOPT_URL, 'https://api.ocr.space/Parse/Image');
curl_setopt($ch, CURLOPT_HTTPHEADER, $request_headers);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, "isOverlayRequired=true&url=http://site.ru/test/captcha.jpg&language=eng");
$result = curl_exec($ch);  
curl_close($ch);
?>

The response is displayed in the browser. although there is no output function. What is it like? It is displayed, of course, on the line:
$result = curl_exec($ch);

Answer 1

curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);