HDMI stands for “High-Definition Multimedia Interface.” It’s a standard that allows TVs to connect to each other wirelessly, allowing you to watch movies and TV shows on your big screen with ease. But what does it mean for your TV? When HDMI is enabled on a TV, all the ports on the back of the TV become available. This includes the port that’s usually used for video input (the left and right channels), as well as the audio output (the left and right channels). The ports on your TV are numbered from 1-3, so if you have an LG TV, there are three HDMI ports available. If you’re not sure which port your TV has, look at the back of the television and see which number corresponds to one of the ports on the front. If your TV doesn’t have a port number at all, it probably means that it doesn’t support HDMI.

An HDMI port is just an HDMI port, right? Except if you peer closely at the back of your HDTV and other HDMI-capable home theater components, you’ll notice quite a few tiny labels that indicate not all ports are equal. What do those labels mean, and does it matter which port you use?

Any Port for the Basics, Specific Ports for Specific Features

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When it comes to selecting which HDMI port to use for which device, there are only a few simple things to keep in mind. First and foremost, when it doubt, always defer to your device’s manual: good labeling, poor labeling, or no labeling at all, the ultimate authority is the fine print the manufacturer has laid out in the manual. Not only might you find that generically labeled port “HDMI 2” actually has extra features, but you may also find you need to toggle a setting somewhere in the TV’s settings menu to enable it.

The second thing to keep in mind is that for older HDMI devices, like your old Blu-ray player or cable box, any HDMI port will work because of backwards compatibility—but some ports offer additional features, which we’ll address in the next section.

Finally, while any port will get the job done for older HDMI-capable devices, you will absolutely want to be sure you’re using best port on your HDTV if you have a newer device capable of 4K input. If you pair a new device with an older port, you’ll miss out on significant quality.

HDMI Labels Decoded

On your typical HDTV set, you’ll find some (though rarely all) of the following labels. While the meaning of the labels ranges from “pretty standardized” to “set in stone” at this point, there is no requirement that manufacturers label their ports at all—if your set simply has “HDMI 1”, “HDMI 2”, and so on, again, check the manual to see if any of the ports have the following features.

STB: Set-Top Box

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The STB port is intended for use with your set-top box: the input device provided to you by your cable or satellite provider. The only benefit of using this port for this purpose is that 1) it’s usually the first port, HDMI 1, which means it’s easy to skip to when using the input selection button and 2) HDTVs with this port designation typically have additional buttons for the set-top box (or additional functionality related to it). For example, your particular TV might use HDMI-CEC to talk to your cable box over the STB port so that the channel up/down buttons on your TV remote will work for your cable box.

DVI: Digital Video Input

DVI ports are an old hold-over from the early days of HDMI, and offer backwards compatibility with devices that can output digital video on one cable but need another cable for audio. The benefit of using the DVI port is that your TV will accept audio input from one (or more) of the analog audio inputs on the back of the TV and match it with the video from the DVI-labeled HDMI port.

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When would you use this feature? Let’s say you had an old desktop computer you wanted to hook up to your TV to serve as a media center. You could use a DVI-to-HDMI cable to output the video signal from the PC to the TV, and then a male-to-male headphone cable to link the audio out on your PC to the audio in on the TV. For more information on connecting your PC to your TV, check out our guide here.

Don’t worry if you have no need for the DVI/analog audio trick, like all the other ports, you can simply use the HDMI (DVI) port as a regular HDMI port as well.

ARC: Audio Return Channel

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Historically, if you had a TV with external speakers, you had a receiver sitting on a shelf under your TV All inputs went to the receiver, and the the receiver would pass along the video signal to the TV. Now, as TVs have increasingly become the hub themselves, people plug everything into the bank of ports on the back of their TV and need a way to get the sound out to additional speakers like, say, a sound bar.

This is where HDMI (ARC) comes in: if you connect two ARC-capable devices together (like that aforementioned HDTV and soundbar) the HDTV can pump audio out to the external device, no separate audio cable (like a TOSlink optical audio cable) required.

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Given how powerful mobile devices have become, like smartphones and tables, it only makes sense that manufacturers developed a way to output video from them to HDTV sets. If you have a compatible device and TV, along with special MHL cable (which allows for USB-to-HDMI connectivity), you can plug your device right into the TV and use it to output video.

The standard is primarily an Android device feature, as MHL was never adopted by Apple. If you wish to achieve similar functionality with your iPhone or iPad, you’ll need to purchase a special adapter from Apple and use that adapter with a regular HDMI port.

HDCP 2.2: High-bandwidth Digital Content Protection

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On newer TV sets, you may see ports labeled “HDCP 2.2”. This designation indicates that this port supports the newest version of the High-bandwidth Digital Content Protection scheme. (HDCP can be quite a headache, especially if you have and older HDTV, by the way, so be sure to check out our guide to HDCP problems if you’ve been having issues.)

If you have newer devices that can output ultra-high definition video, you will likely need to use this port (or check the manual to see if all your TV’s ports support HDCP 2.2) in order to get the signal and enjoy your UHD content.

10bit/UHD/4K: An Enhanced Port for Enhanced Video

Newer TVs that support 4K, also called Ultra HD (UHD) by some manufacturers, don’t always have 4K capabilities on all the HDMI ports. Sometimes you’ll find only one port labeled to indicate that’s the one you should use for your shiny new 4K-capable streaming device.  How these ports are labeled is up to the manufacturer and you’ll see labels like “10bit”(in reference to the enhanced 10-bit color range that some some, but not all, 4K content can support), “UHD”, or 4K (often coupled with additional information like 4K @30Hz or 4K@60hz to indicate what refresh rate the input can use). Ultra High Definition video is still pretty new territory and manufacturers are scrambling to both cash in and distinguish themselves from each other, so be sure to check the manual for your TV to ensure you’ve got the right port and the right settings to get the most out of your UHD content.

BEST: Relative Designation

Finally, there’s another label you may see by your HDMI port that has nothing, specifically, to do with HDMI standards, but is simply a way some manufacturers label the ports on the back of their TVs. On many sets, you’ll see a sequence of comparison and superlative adjectives like “Good”, “Better”, and “Best” attached to different ports.

You may, for example, see the component input labeled “Good”, the regular HDMI input labeled “Better”, and the HDMI 4K input labeled “Best”. These labels have no standardized meaning, and are simply there so the manufacturer can steer you towards using the best port (if it is compatible with your device) so you get the best picture quality.

While all HDMI ports will give you basic and backwards-compatible functionality, by pairing the right port with the right device you’ll get the best possible picture with the best possible features.