HDMI stands for High-Definition Multimedia Interface. The connector, and the cable that goes with it, carry video and audio between two digital devices over a single connection.
It is found on desktop monitors, laptops and desktop computers, TVs, game consoles and set-top boxes. Its trapezoidal 19-pin shape is the same everywhere, which explains why the same cable can be used from one device to another. What changes from one connector to another is its version, and therefore what it can display.
What High-Definition Multimedia Interface means
Each of the three words in the acronym describes part of what the connector does.
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High Definition: the connection was designed to carry high-definition digital video, whereas the connectors that came before it were limited to lower resolutions or used an analog signal.
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Multimedia: it carries video and audio together. This distinguishes it from older video connectors, which required a separate audio cable.
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Interface: it is a standardized connection defined by a common specification, allowing devices from different brands to communicate without configuration.
The acronym can be written with or without a hyphen between High and Definition. Both forms refer to the same thing.
What the connector carries
An HDMI connection carries video and audio over the same cable. Video is described by two numbers: resolution, meaning the number of pixels displayed, and refresh rate, meaning the number of frames per second. Audio follows the same path, allowing sound to be sent to the monitor's speakers or headphone jack.
On a desktop monitor, this single connection replaces the two cables used in the past, one for video and one for audio. For this reason, an HDMI-connected monitor appears among the computer's audio devices, just like a headset.
What the version changes
The HDMI specification has evolved through successive versions, numbered 1.0, 1.2, 1.4, 2.0, and beyond. Each version increases the bandwidth the connection can handle, and therefore the combination of resolution and refresh rate it can display.
In practice, the same trapezoidal connector may be limited to Full HD on an older machine and display 4K on a newer one. The shape says nothing about the level: only the version indicates it, and this is listed in the device's specifications.
The key point to remember before buying is that the lowest version in the chain determines the result. A recent output on the computer, a recent input on the monitor, and an old cable between the two: the entire connection behaves according to the cable.
Where to find the version on a monitor's specifications
The technical specifications of a monitor list its inputs and, for each one, what it supports. The answer is there, not in the photo of the back of the monitor.
The 27-inch 4K UHD monitor with USB-C, model JN-IPS27UHDR-C65W-HSP-W, for example, specifies HDMI 2.0 at 3840 x 2160 and 60 Hz. The line is read in this order: the connector version, the maximum resolution it can display, and the refresh rate at which it can display it. The same monitor features USB-C 3.1 at the same level and a DisplayPort, leaving the choice of connection depending on the computer being connected.
Two figures are worth comparing with what you already have. Resolution first: a 31.5-inch 4K UHD monitor requires an output capable of producing it; otherwise, the image will be displayed at a lower resolution. Then refresh rate, which determines the smoothness of scrolling and pointer movement. The details of what 4K encompasses are covered in our article on 4K resolution.
One output on one side, one input on the other
The connection has a direction. The computer has an output, which sends the video. The monitor has an input, which receives it. Specifications sometimes use the English terms “HDMI out” on the source side and “HDMI in” on the monitor side, and connecting two outputs together will display nothing.
A desktop monitor often has several inputs, allowing two computers to remain connected permanently. A TV may have even more for the same reason. On a laptop, the connector is almost always a single output, so a second monitor then requires USB-C or a docking station.
The three connector sizes
The specification defines three connector formats for the same signal.
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The standard format, known as Type A, used on desktop monitors, TVs and desktop computers.
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The Mini format, which is smaller and found on some cameras and compact devices.
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The Micro format, which is smaller still and used on portable devices and development boards.
A cable or adapter can connect one format to another without changing the signal being carried. The connector size therefore says nothing about the connection's performance: it reflects the device's space constraints, not its capabilities.
The cable matters just as much as the connector
An HDMI cable is not just a simple wire. It also has a performance level, indicated on its packaging or sheath, and a cable designed for a lower resolution can limit the entire connection.
Three symptoms can indicate a cable problem: an image displayed at a lower resolution than the monitor supports, an image that flickers or disappears intermittently, or a refresh rate stuck at a low value in the system's display settings. Length also matters: the longer the cable, the more the signal can degrade, and a model certified for the required length removes the uncertainty.
What the connector does not determine
The connection carries the image; it does not create it. Perceived image quality first depends on the panel, its resolution, and how it reproduces colors and contrast. Two monitors connected through the same HDMI port, with the same cable and the same computer, will not display the same image if their panels differ.
This is why the panel type should be considered alongside connectivity when choosing a monitor, as explained in our comparison of IPS panels and VA panels. The connector ensures that the image arrives; the panel determines what it becomes.
