HD is the term used to differentiate the systems that generate, transmit or support HD content (High Definition) with those of standard definition or low definition (SD).

HD resolutions are usually at least 1280 x 720 pixels by taking the ratio "width x height". Being the height, 720 pixels, which make high resolution.

The acronym "HDMI" stands for "High Definition Multimedia Interface".

The HDMI interface allows transmission of video and audio between devices, supporting video resolutions 480i, 480p, 576i, 576p, 720p, 1080i, 1080p, 1440p, 1600p.

Different HDMI versions

HDMi 1.0
- December 2002.
- Maximum transfer of 4.9 Gbit/s.
- Supports up to 165 Mpixels/s video mode (1080p or UXGA 60Hz) and 8-channel/192 kHz/24-bit audio mode.

HDMI 1.2
- August 2005.
- Added support for One Bit Audio, used on Super Audio CDs, up to 8 channels.
- Availability HDMI Type A connectors for PC.

HDMI 1.3
- June 2006
- Bandwidth 340 MHz.
- Data rate of 10.2 Gbit/s.
- Dolby TrueHD and DTS-HD,

HDMI 1.4
- Send video and audio HD
- Data and 3D video.
- FullHD to XHD (eXtended High Definition) up to 4096 × 2160 pixels (24 frames per second) or 3840 × 2160 (30 fps).
- Audio Return Channel that will need fewer cables to have a surround sound system connected to the TV.
- Built-in Ethernet connection cable with speeds up to 100 Mbit/s own.

HDMi 2.0
- September 2013
- Bandwidth of up to 18 Gbit/s
- 4K @ 50/60 (2160p) video
- Up to 32 audio channels to a multi-dimensional immersive experience
- Up frequency 1536kHz for maximum audio fidelity sound
- Simultaneous Delivery 2 streaming video to multiple users on the same screen
- Streaming audio up to 4 users
- Support theater angle 21:9 radio
- Dynamic synchronization of video and audio in streaming
- Extensions of CEC commands to control multiple devices from a single point.


Type HDMI

Type A (picture 1): It is the standard connector used in almost all devices.
Type B (picture 2): A connector rarely used.
Type C (picture 3): A connector widely used in tablets, smartphones and other devices.
Type D (picture 4): A connector used in smartphones.
Type E (picture 5): IA connector used for vehicles connectivity.

The meaning would be HDTV. It is used to indicate that the device is compatible with high definition. For high definition they have created three technical standards. ATSC, DVB and ISDB-T. Since 2005 the possibility of assigning HD Ready label as a kind of obligation to define the devices that have more than 720 lines (720p, 1080i at 50 or 60 Hz) was assessed.