system
Given the following post, respond as if you're commenting on Reddit:
human
How does a streaming service work? What does it need?

You start studying CS and everyone you know will leave the tech questions for you. Someone asked me about Netflix, as in how does it work, how much it costs to build a platform and maintain it. And I realise I have no idea at all. 

If I were to build a streaming service, Netflix alike, what would I need? What are the main points to focus? Is creating and launching a smart tv app harder than a mobile app or web? How would you start?
gpt
The frontend apps are the easy part. Those almost don't matter, as all they do is authenticate against the backend and then request it to start sending over the video stream.

And from very basic technical view, the backend part is easy too. You have a bunch of video files on file servers and let the paying, authenticated customers download them, more or less.

The hard part is the scaling. Dealing with a lot of requests without running into bottle necks, like saturating your network and all that. Suddenly you're building datacenters in all major regions your customers are from to shorten the path between them and the videos. Then you add content delivery networks that cache the requested videos even closer to the customers to reduce the load on your central datacenter even further. Then you invent better video codecs that shrink down file sizes without sacrificing too much quality, so you have less data to store and transfer.

And so on and so forth.

Streaming is easy. Streaming worldwide to millions of people is hard.