I know that with XM/Sirius it's a subscription, and it's commercial-free radio. A myriad of stations and topics. Everything from music, to talk shows, sports and comedy. You can get the same subscription to your phone and home. The home requires a box similar to digital tv.

You can access music online, Spotify, etc. I think most of them require a subscription as well.

I like I(heart)radio. It's a free app available for Apple or Android devices. You can choose the genre that you prefer and rate songs that you like so that you'll hear them again.

I'm not sure what "streaming radio" refers to, but I know many if not most radio stations maintain websites where you can stream the current show live on your computer or devices. You can also listen to previous shows from their archives.

There are also websites where you can order up music of your choice to create "radio stations" (not really) that play music you like. I use Pandora. I Heart Radio sounds similar.

"You can just listen on your computer, tablet or smart phone?"

Yes - that's exactly how they work. Pandora, Slacker and Spotify are websites to connect to, and most have custom apps for most hardware types beyond just PCs. The signups are free.

They have a multitude of preconfigured genre stations, but in addition users can have personally customized stations - Say you want to listen to Beatles music, you create your own "station", give it a name, and tell them what artists to include. If a song comes up you don't like, there's a place to click that says "Don't play this song again on this station". If a song comes you up don't want to listen to at the moment but you do at a later time, you can skip on to the next song on the playlist. Each site will remember your stations and preferences for use at a later date.

Sites like I Heart Radio and TuneIn are different, they aggregate streams of broadcast stations so that you can find them all in one place. You're in Denver, but like a radio station located in Seattle. If the Seattle station provides an internet stream, these two sites (and others) allow you to listen to it. Most radio stations block live sports broadcasts, so it's not a way to listen to your favorite Dodgers play-by-play when you're in London.

"The article mentions "home audio systems." Are there systems which hook up to wi-fi so you can listen to music that way?"

Exactly. If you want just a stand-alone player in your kitchen, for example, take a look at products (called Internet Radios or Wifi Radios) by Sangean or Grace. If you want a more comprehensive system to connect to a stereo or standalone speakers and to play a digitized music collection IN ADDITION TO the above discussed internet sources, then consider Sonos or Apple Airport Express. Both of these different types of products can be controlled from a PC, but they also have apps that allow you to control them from any tablet or smartphone.

Also, some TVs or disk players come with Pandora or Slacker apps, to stream the music through the TV.

With a smartphone and a Pandora or similar account, you can connect the phone to your car's audio system (through Bluetooth, or an AUX or USB connection) and continue to listen to the internet sound source while you drive.

We use them constantly as we often are working away at something or other around here. We hook up my husband's cell to a Bluetooth speaker and we most often use Spotify. It is a free service or you can do a paid service. The free one you can only skip so many songs so if there are a bunch of songs you can't stand and you skip them, you'll have to wait to get more skips. I'm not sure what the paid service offers. Before this we use to often just stream from our favorite alternative radio station.

Streaming radio is pretty much like streaming video. If you order movies over the internet at home via Netflix, Amazon Prime, or similar, well it's the same thing. Often your cable or internet service will offer music stations as well as video, and you can play them through your tv.

I stream music through ITunes radio, Amazon Prime Music, and Pandora. You can choose your "stations" -- I listen to them from my computer at home or work, and through my phone, either with headphones, or via bluetooth. It's a nice addition to the music I've collected on CDs or downloaded over the years.

My "home audio system" is basically my Mac and ITunes. I also have a great wireless speaker called Sharkk boombox. Take your music anywhere.