by If you’ve shopped for an HDTV, Playstation, or HD-DVD or Blu-ray player, you’ve probably heard of HDMI. Before we go too far, you’re probably thinking, “What does HDMI stand for?” The answer is “high-definition multimedia interface,” and it’s one of the many connections on televisions or home theater receivers.
But HDMI is also more than just a port on the back of your TV (or a cable to connect your device to the screen). It’s a set of rules that revolutionized the way people transmit video and audio signals, providing a single-cable solution to a multitude of consumer electronics.
HDMI Basics
At its core, HDMI is a proprietary audio and video interface for transmitting uncompressed video and audio streams between compatible devices. It serves as a digital replacement for earlier analog standards, such as video graphic array (VGA) and component video.
Manufacturers debuted the first HDMI version (HDMI 1.0) in 2002. Since then, almost a dozen revisions have been made, including the following important updates:
The HDMI interface consolidates video transmission, audio output and other data in one cable. This not only simplifies things but also allows for high quality audio to be transmitted, resulting in a higher quality viewing and listening experience overall.
The HDMI standard was created by a group of electronics manufacturers as a set of guidelines for creating high-bandwidth connections between digital devices. With the right setup, HDMI can make a significant difference in a home theater system.
HDMI and 8K
The current standard (HDMI 2.1) can transmit up to 48 gigabits per second and easily supports 8K (7,680 x 4,320 pixels) or 4K (3,840 x 2,160 pixels) resolutions with refresh rates much higher than the original HD (1,920 x 1,080 pixels).
For example, you can watch 8K resolution at a 60Hz refresh rate, or you can watch 4K resolution with a 120Hz refresh rate to get your perfect balance of crystal clear video and ultra-smooth action.
HDMI can cut down on the number of cables needed to connect components, and can even reduce the number of remote controls you need to watch a movie.
Different Types of HDMI Connectors
HDMI connectors come in different types to suit different devices and use cases. Each type caters to specific device categories, from standard consumer electronics to portable devices.
There are different types of HDMI cable that correspond to the different types of HDMI connectors. The five main types of HDMI connectors include:
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HDMI Type A (standard): The standard HDMI connector, also known as Type A, is the most common and widely used of the five HDMI connector types. You can commonly find standard HDMI connectors in Blu-ray players and home entertainment systems.
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HDMI Type B: Intended to carry dual-link DVD-I video, this connector became obsolete almost immediately after its release in the early 2000s, due to advances in technology, so does not use it is any consumer products.
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HDMI Type C (mini): You’ll find a mini HDMI connector on portable devices, such as cameras, tablets and other small items that require HDMI connections.
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HDMI Type D (micro): Even smaller than a mini HDMI connector, a micro HDMI connector is for use in very small, highly portable devices, such as mobile phones.
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HDMI Type E (automotive connection system): You can find these HDMI connectors in cars. They have a special design that makes them better able to preserve audio-visual quality despite the vibrations associated with driving.
What Do HDMI Cables Do?
HDMI cables support a range of features and capabilities, such as:
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High-speed HDMI cables: Handle high-definition video transmission and an enhanced audio return channel.
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HDMI ethernet channel: Allows sharing of an internet connection between HDMI devices.
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Audio return channel (ARC): Enables bidirectional audio transmission between HDMI-connected devices, eliminating the need for separate audio cables.
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HDMI alt mode: Facilitates HDMI connectivity over alternative interfaces such as USB-C, expanding compatibility with modern devices.
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Enhanced audio return channel (eARC): Improves sound quality and bandwidth for immersive audio experiences, especially with formats such as DTS HD master audio and DVD audio.
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Consumer electronics control (CEC): Allows control of a device via a single remote control, streamlining user interaction in interconnected settings.
You’ll find HDMI across a wide spectrum of devices and uses, including portable devices like smartphones, tablets and laptops. Here, HDMI ports enable you to watch video on an external display.
For example, you might want to stream a movie on your laptop but watch it on your desktop monitor. To do this, you will need to connect the two with an HDMI cable.
Likewise, a standard HDMI cable or a high-speed HDMI cable has become an integral part of most home entertainment systems, connecting Blu-ray players, streaming devices, video game consoles and ultra-HD televisions.
Outside the home, you’ll find HDMI use in professional audio-visual settings, supporting video transmission in commercial displays, projectors and conference room settings.
Standard Definition: The Precursor to High Definition
HDMI technology and high definition televisions are now ubiquitous, but it wasn’t always that way.
Before HDTVs were developed, most televisions displayed pictures in what people refer to as standard definition. The picture was almost square, with an aspect ratio of 4:3. Its resolution, or the number of dots in the picture on the screen, was about 704 x 480 pixels.
In standard definition, each piece of a moving image was half a picture, but the pictures changed fast enough that the human brain didn’t really notice. These older televisions relied on analog signals, which travel as an ever-changing electrical current.
The rise of High Definition
In contrast to standard-definition televisions, HDTVs are digital. They use information in the form of ones and zeros. This information travels through cables as separate electrical pulses.
HDTV has an aspect ratio of 16:9, so the picture is more rectangular. They also have a higher resolution: Current HDTV standards allow for a resolution of up to 1920 x 1080 pixels.
HDTV signals can also be progressive, meaning that each frame of the moving image is a full picture, rather than just half of a frame.
So, compared to standard TVs, HDTVs have a wider screen, more pixels and a faster refresh rate.
Often, HDTVs can display more colors than older sets. This means that HDTVs require more data and require it much faster than standard-definition televisions. If an HDTV can receive this information digitally, it doesn’t need to spend time or processing power converting the signal from an analog format.
The future of HDMI
Since its inception, HDMI has undergone several revisions to keep up with advancing technologies. The HDMI Forum, which is responsible for the development of the HDMI specification, continuously updates standards to support emerging trends such as 8K resolution, high dynamic range (HDR) and enhanced gaming features.
Looking ahead, this type of digital interface is set to become the de facto standard for high-quality audio-visual connectivity, ensuring seamless integration across a multitude of devices and applications.
As consumer electronics continue to evolve, HDMI will no doubt continue to adapt so that people can continue to enjoy compatibility among their many devices and systems.
We created this article in collaboration with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.
Basics: What Does HDMI Stand For? This is how HDMI works
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