So the Internet only works because digits are transmitted with perfect reliability, or it absolutely breaks. I can't read your post here on Audiogon, I can't save it, and I can't do anything unless this is true.
Now, as for real time playback, like with Netflix or Hulu, or music, real time buffering is key. You've been to a website, and sometimes it's slow, and sometimes it's fast, or sometimes some parts are fast, and others are slow.
So, for video and audio, there has to be some buffering and sometimes resolution trade offs.
So, hidden from you, is a stream that gets data as fast as it can and puts it in a bucket. There's another stream which actually feeds your TV or DAC, which dolls it out at a steady rate.
In general, this is pretty reliable and really good. I mean, when you consider the quality of sound from Bell's first speaker and microphone to today, things are spectacularly better. And 5.1 on a Netflix stream? Forget about it. It's magic.
Next, a lot of tech has gone into high quality DAC's to get that stream as smooth as possible. Over the last 10 years, this part, related to reducing jitter, and high quality clocks, has gotten REALLY good.