irDA is known in one of the following two meanings:
1. A standard for transmitting data, originally designed for use with infrared (non-visible) light technology. Transfer speeds are roughly the same as traditional parallel ports.
Infrared connectivity is an old wireless technology used to connect two electronic devices. It uses a beam of infrared light to transmit information and so requires direct line of sight and operates only at close range.
IrDA, together with infrared, was used to wirelessly connect the phone to various devices, to exchange information such as phone book entries with other phones. Finally, some phones can also use it to send information such as phone book entries and calendar events to Infrared-equipped printers.
Infrared was once common in laptop computers, but is almost unheard of now. Computers without infrared required a USB infrared adapter to communicate with a phone via infrared.
Many home devices such as TVs and DVD players still use IR remote controls. Some smartphones are capable of using their IR port to control these devises but that usually requires third-party software.
IrDA over infrared was essentially replaced by Bluetooth, which has a longer range (around 30 feet) and being omni-directional. Bluetooth does not require line-of-sight since it uses radio waves instead of light.
2. The industry group that created the IrDA technical standard.