Digital Living Network Alliance (DLNA) is nonprofit organization aimed to establish a common standard for sharing and playing media files (video, music, photos) over network among various devices. (Read more on Wikepedia).

The client device (TV, blu-ray, game console) connects to your home computer over network for browsing and playing available media files.

The server computer should have special software installed (like iSedora Media Server) to provide clients with media files.