In terms of milestone events, you might look into things like the first viruses, the birth of e-commerce and the development of SSL, social media pre-Facebook,

In terms of milestone events, you might look into things like the first viruses, the birth of e-commerce and the development of SSL, social media pre-Facebook, the first DotCom implosion, the advent of "Web 2.0," etc. (though precise dates for these may be debatable). Unfortunately I'm coming up empty when trying to remember more positive developments that had a broader impact and aren't narrowly commercial, and it may be that the nature of these is a more gradual process (and part of why we hear about "good news" less frequently).