High-Definition Multimedia Interface (HDMI) is a standard used in audio and visual equipment like high-definition televisions and home theatres. Hot swapping means plugging or unplugging a piece of electronic equipment without first manually turning off the power. There are benefits to hot swapping like decreased downtime of websites and less time exchanging cables, but not all devices are hot swap capable.
An HDMI cable is composed of 19 wires enclosed by protective insulation into one. It can be identified by the tip, which is smaller than related audio and visual cables like DVI and VGA and similar to a USB connector in size and shape. The tip of the cable has 19 pins where the connection is made to an electronic device. Each pin serves a different purpose in the transmission of a signal. One of these pins is called "Hot Plug Detect," and is dedicated to monitoring when power is turned on or off or when cables are plugged or unplugged.
The purpose of hot swapping is to remove and replace a drive or cable with a minimum of interruption to a system. Devices that are hot swap capable allow you to connect and disconnect them while power is still turned on, or "hot." If equipment that is not hot swap compatible is unplugged or plugged in while power is still running, damage may occur.
Example of Importance
Most websites are stored in remote locations known as servers where many other sites are stored. When a user requests to connect to and browses a website, he makes a connection with that remote server. As with any electronic hardware, hard drives eventually fail and need to be replaced. If the hard drive replacing the failed one is hot swappable it can minimise the impact of the failure.
Common devices that are hot swap capable are (most) server hard drives, USB cords, firewire cords, optical drives like CD-ROM and DVD-ROM, modems, routers, and portable storage like SD cards. In theory, HDMI cables should also be hot swappable. This is because one of the 19 pins is a five-volt ground that makes or breaks connections safely. However, in practice it's best to avoid hot swapping HDMI whenever possible because not all cables are created equal, and lesser equipment can potentially destroy port electronics when hot swapping.