DLNA is a standard that defines how devices can share, play, store, record and control audio and video, over a computer network. Devices are consider to be producers, meaning they can provide the multimedia content, or they are consider consumer, meaning the can take the multimedia content to handle in some manner, or finally as a controller that can direct the producers and consumers. This standard is very extensive and provides a set of tests that any DLNA Certified device must pass in order to be certified.
Imagine being able to use your smartphone to tell your network storage device to stream a movie to your TV, in your living room. At the same time using your phone to tell your MP3 player to stream music to your refrigerator to play music in your kitchen while you cook. Additional your Phone is sending photos you took that day to display in your electronic photo frame in your entry way. Can we say connected?
I would advise anyone looking at buy new Audio/Visual equipment to take a look at DLNA: