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    <p><strong>Answer one</strong>, your logic is correct: second event will wait. And will execute as far as its queued callbacks time comes.</p> <p>As well, remember that there is no such thing as "simultaneously" in technical world. Everything have very specific place and time.</p> <p>The way node.js manages thousands of connections is that there is no need to hold thread idling while there is some database call blocking the logic, or another IO operation is processing (like streams for example). It can "serve" first request, maybe creating more callbacks, and proceed to others.<br> Because there is no way to block the execution (except nonsense while(true) and similar), it becomes extremely efficient in spreading actual resources all over application logic.</p> <p>Threads - are expensive, and server capacity of threads is directly related to available Memory. So most of classic web applications would suffer just because RAM is used on threads that are simply idling while there is database query block going on or similar. In node that's not a case.</p> <p>Still, it allows to create multiple threads (as child_process) through <a href="http://nodejs.org/api/cluster.html"><code>cluster</code></a>, that expands even more possibilities.</p> <p><strong>Answer Two</strong>. There is no such thing as "loop" that you might thinking about. There will be no loop behind the scenes that does checks if there is connections or any data received and so on. It is nowadays handled by Async methods as well.</p> <p>So from application point of view, there is no 'main loop', and everything from developer point of view is event-driven (not event-loop).</p> <p>In case with <code>http.createServer</code>, you bind callback as response to requests. All socket operations and IO stuff will happen behind the scenes, as well as HTTP handshaking, parsing headers, queries, parameters, and so on. Once it happens behind the scenes and job is done, it will keep data and will push callback to event loop with some data. Once event loop ill be free and will come time it will execute in node.js application context your callback with data from behind the scenes.</p> <p>With database request - same story. It ill prepare and ask stuff (might do it even async again), and then will callback once database responds and data will be prepared for application context.</p> <p><strong>To be honest, all you need with node.js is to understand the concept, but not implementation of events. And the best way to do it - experiment.</strong></p>
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