"Man, the internet sure has changed!" You say or hear that statement quite a lot. It's true that new technology, shared experiences, and cultural shifts take place at the speed of light thanks to the ease and reach of the internet. When so many changes take place in just a few years, you can lose track of what once was. Quick, do you recall which came first- Napster or Wikipedia or wifi? Those milestones seem to exist in a lump now, although the internet we have now evolved in a series of steps. I remember when we talked about "web 2.0" for a long time before the term "social media" was settled on, and it wasn't all that long ago.
Mental Floss has a refresher on the subject of internet history, with 20 milestones that may strike you as profound, or maybe just nostalgic. At any rate, they help to explain how we got where we are today.