With Apple's AirPlay technology, you can wirelessly stream audio and video from the iTunes software or other enabled apps on your iOS device (such as an iPhone) or from a Mac or PC.
The streams go to AirPlay-compatible devices such as an Apple TV, certain audio-video receivers, and some speakers. And soon you'll be able to stream anything playing on a Mac.
What do you need to make it work?
AirPlay requires three elements: a wireless network, an AirPlay-sending device (like an iPhone with iOS 5 software) and an AirPlay-receive device. Both sending and receiving devices must be on the same Wi-Fi network.
AirPlay-receiving devices include the $99 Apple TV for audio and video and Apple's $99 Airport Express for audio. Several other companies have adopted the technology, as well. You'll find audio-video receivers with AirPlay from companies including Denon and Pioneer, as well as AirPlay speakers from Bowers & Wilkins, Klipsch and others.
How does it work?
An AirPlay icon appears on the screen when you play media through iOS apps such as Music or Video or other AirPlay-enabled apps, such as Netflix, Pandora Radio and PBS for iPad. Just touch the icon to select the device you want to send the stream to.
Once they are connected, you can control playback and volume through either the sending or receiving device. So you could have the computer in another room but still control playback from the TV you are watching, for example.
What is AirPlay Mirroring?
Mirroring takes what appears on the screen of your iOS device and displays it on a television connected to an Apple TV receiver.
AirPlay Mirroring first appeared last year with iOS 5 and gets a boost with the release of the new Mountain Lion operating system for Macs, due buy the end of this month.
With an Apple TV connected to an HDTV, you can stream what you see on your Mac's screen at up to 1080p high-def video quality. So even if you don't have an Internet-connected "smart TV," you'll now be able to watch Web video, such as Netflix, on the big screen.
Not everyone will get AirPlay Mirroring in Mountain Lion, however. Only Macs from 2011 or later have the processing power it takes. You also need a second-generation or newer Apple TV (the small "hockey-puck" version) to receive the stream.
Will AirPlay last?
Thanks to its added features, ease of use and increasing adoption in home theater equipment, AirPlay looks likely to become more important in the next few years.
Expect more receivers and speakers to adopt it — and don't be surprised to see some HDTVs and computer monitors with it built-in, as well.