How does accessing external data in a PHP website impact traffic usage for both the server and the user?

Accessing external data in a PHP website can impact traffic usage for both the server and the user because it requires additional requests to external servers, which can slow down the website's loading time and increase server load. To mitigate this, you can implement caching mechanisms to store the external data locally and reduce the number of requests made to external servers.

// Check if the data is already cached
if (file_exists('cached_data.json')) {
    $data = file_get_contents('cached_data.json');
} else {
    // Fetch the data from the external server
    $data = file_get_contents('http://external-api.com/data');
    
    // Cache the data locally
    file_put_contents('cached_data.json', $data);
}

// Process and display the data
echo $data;