For anyone who's ever tried to fetch multiple resources over HTTP in PHP, the logic is trivial, but one key challenge is ever-present: latency delays. While web servers have perfectly good downstream links, latencies can increase script execution time tenfold just by downloading a few external URLs. But there's a simple solution: parallel cURL operations. In this tutorial, I'll show you how to use the "multi" functions in PHP's cURL library to get around this quickly and easily.
He starts with a basic cURL example, grabbing the content from example.com and putting it into a variable. He modifies this to make it a bit more complex and to run multiple fetches in parallel - creating more than one cURL object and using the culr_multi_* methods to manage them.