PHP

php set header content type html

// set header to HTML (default)
header("Content-Type: text/html");

// set header to Text
header('Content-type: text/plain');

header content type html php

header("Content-Type: text/plain");
echo "<b>hello world</b>";
// Displays in the browser: <b>hello world</b>

header("Content-Type: text/html");
echo "<b>hello world</b>";
// Displays in the browser with bold font: hello world