Is it necessary to use & instead of & in PHP URLs for validation purposes?

Using & instead of & in PHP URLs is not necessary for validation purposes. Both symbols are commonly used to separate query parameters in URLs, and PHP will interpret them correctly regardless of which one is used. However, using & instead of & can help ensure that your HTML code is valid and properly displayed in browsers, especially when the URL is included in an HTML attribute.

$url = "http://example.com/page.php?param1=value1&param2=value2";
echo $url;