since saratoga mentioned it (which I think is a pretty good ball park figure to)... I think the first smart phone (from Apple) was pretty much 2007, which means it was a fair amount past that before they really went mainstream. so with that said, that should roughly mean it's been about 10 years since smart phones have been mainstream. so one could say basic cell phones were in the 2000's and smart phones the 2010's for the most part since the more earlier days of the common person getting a basic cell phone were late 1990's (probably 1997-1998).
I remember the Napster thing which, taking a quick look online shows 1999, which was probably then or maybe 2000 or so when I was aware of it and then, like Chibisteven said, RIAA etc suing people etc.
but from a look online... it appears CD sales peaked in the year 2000 (speaking for myself... a high percentage of the CD's I bought were late 1990's, or maybe a touch into the early 2000's). we got our first CD player in about 1992 (I know it could not have been any more recent then probably the earlier side of 1993 though, but it's almost surely either 1991 or 1992, which I would estimate the early 1990's is probably when AUDIO CD's started to go mainstream) as I would have been going into my teens.
but anyways, back to the CD sales chart... even though they peaked in the year 2000 (call it about 900million+ CD's sold in the year 2000, where as in 2020 it was about 31.6million. so you can see a significant drop in CD sales), it seems sales were still going strong for quite a while past that. even today I don't see CD sales completely dying (at least not for a while) as they still make enough $ given this general chart... https://cdn.statcdn.com/Infographic/images/normal/12950.jpeg
p.s. but I think this stuff basically plays inline with modern tech in general as cellular phones/computers/internet went mainstream about 1998-2000 (my first computer was 1995, so I was on them about 3-5 years before they were mainstream). in fact, in my area high-speed internet was available in the year 2000 as I was one of the earlier people to get it according to the guy who installed it. so my 1998-2000 estimate should be a pretty good guideline for how long modern technology has been around as I was around 20 years old back then. but it's funny as it feels like modern tech (i.e. basic cell phones/computers/internet) has been around a rather long time but it's really only been around not much over 20 years for the common person now. so call it about half of my life or a bit over that now. it's like how did we make it in the "old days" without it since many of us are at least semi-addicted to it