What resources or documentation can be helpful for understanding how to load multiple pages into a single document using PHP without using iframes?

When loading multiple pages into a single document using PHP without iframes, one approach is to use the `file_get_contents()` function to fetch the content of each page and then concatenate them together. This can be done by storing the URLs of the pages in an array and looping through them to fetch and append the content.

<?php
// Array of URLs to load
$urls = array(
    'page1.php',
    'page2.php',
    'page3.php'
);

// Loop through each URL and fetch the content
$combinedContent = '';
foreach ($urls as $url) {
    $content = file_get_contents($url);
    $combinedContent .= $content;
}

// Output the combined content
echo $combinedContent;
?>