When Netflix first started streaming movies and TV shows back in 2007, most people didn't have any way to watch that stuff on their television sets. We were all still using DVD players back then — the only way to watch Netflix on a real TV was to plug a whole computer into the TV and use the screen like a giant computer monitor. Or, at least, that was the situation until Roku came along. Roku released its first streaming device shortly after Netflix kicked off the streaming revolution, and the rest is history. Today Roku remains primarily (but not exclusively) a streaming hardware and platform company. Let's take a look at Roku's streaming devices, what you can watch on Roku, and what other products Roku has to offer.The Roku platform“Roku” is the name of the company, but it's also the name of the streaming platform and a brand name that gets slapped on the devices that run that streaming platform. Got it?It's a little confusing! Let's back up and talk about what a streaming platform is.When we talk about Roku a streaming platform, we mean the operating system and user interface that you see when you use a Roku device. Roku, like all streaming platforms, is something that helps you access streaming services like Netflix and Amazon Prime Video. Roku is not, generally speaking, responsible for providing TV shows and movies itself. The idea is to organize the stuff that everyone else is offering, so that you can access all of your subscriptions on your TV and without having to constantly change hardware and TV inputs around.As you might imagine, this means that the most important thing that a streaming platform can do is to support a lot of different apps.So what services can you use you watch TV shows and movies on Roku? A whole lot. Roku's massive app library is one of the main reasons for its enduring appeal. And Roku is a relatively “agnostic” platform: it doesn't push users toward specific apps in the same way that, for instance, Amazon's Fire TV platform pushes users toward Amazon apps and services.Roku's apps — which Roku calls “Roku Channels,” by the way — include all of the major video streaming services and just about all of the minor ones, plus apps for streaming music, viewing photos, and more. The only sorts of apps that Roku is arguably a little short on are games.Roku channelsAmazon VideoDirecTV NowESPNHBO GoHBO NowHuluNetflixPlayStation VueSling TVSpotify…and much moreAgain, these are “Roku Channels” or apps, not channels in the sense that cable and skinny bundle services have channels. So when we say “ESPN” we mean the ESPN app, which you can use to watch clips and use your ESPN+ subscription if you have one — it's not a live feed of ESPN's cable channel or anything like that.What devices can I use to watch Roku?The Roku platform is accessible through Roku's selection of streaming hardware. The lineup includes streaming boxes, streaming sticks, and smart TVs that come with Roku already on board — no meddling with HDMI inputs required.Here's a look at Roku's current streaming device lineup.Roku streaming devicesRoku Express & Roku Express+Price: $29.99 (Express) or $35 (Express+)These devices are your most affordable path to the Roku streaming platform. They're small, portable, and great for folks on a budget. The hardware under the hood is pretty much the same in both models. The difference here is that the Express+ has VGA cables (those red, white, and yellow ones that old VCRs and video game systems had) instead of the typical HDMI connection. If you have an old TV without an HDMI input on it but still want to stream, the Express+ is the one to go with. Otherwise, get an Express or one of the others on this list.Roku Premiere & Premiere+Price:$39.99 (Premiere) or $49.99 (Premiere+)The Roku Premiere packs better hardware into the same form factor as the Roku Express. The current models are both 4K- and HDR-capable. The difference here is the remote: the Roku Premiere+ has a better one that features a power button for your TV.Roku Streaming StickPrice: $49.99The Roku Streaming Stick is more powerful than the Roku Express. It's great for streaming in 1080p HD, and it has a solid Wi-Fi antenna to help keep things smooth.Roku Streaming Stick+Price: $59.99Why the plus? Because the Streaming Stick+ builds on its little brother's specs and features improvements like a special Wi-Fi antenna that is built into the power cord in order to reduce interference from your TV. This is Roku's most affordable 4K-capable streaming device.Roku UltraPrice: $99.99Roku's elite streaming device has it all: 4K Ultra HD, HDR, Dolby Audio, and more. You can even use a headphone jack on the remote for private listening or connect the device to an Ethernet cable to swap your Wi-Fi out for a more reliable wired connection.Roku TV smart TVsPrice: VariesRoku's platform has long put the platforms on most smart TVs to shame. But now the Roku platform is on a smart TV — several, in fact. Roku partnered with a few different manufacturers, including TCL, to produce the “Roku TV” line of smart TVs. You'll find options at all different sizes and price points.Roku audioRoku has focused almost exclusively on streaming for more than a decade, but it wouldn't be quite fair to say that streaming platforms and hardware are all that the company does. Roku recently broke into the speakers market.Roku audio productsRoku TV Wireless SpeakersPrice: $199Roku's speakers have been well-received and will work great with your Roku TV. The downside? The Roku TV Wireless Speakers will work only with Roku TV models. Other TVs (and even other smart TVs) need not apply.