The HD ready is a certification program introduced in 2005 by EICTA (European Information, Communications and Consumer Electronics Technology Industry Associations), now DIGITALEUROPE.
There are currently four different labels: "HD ready", "HD TV", "HD ready 1080p", "HD TV 1080p". The logos are awarded to television equipment capable of certain features.
In the United States, a similar "HD Ready" term usually refers to any display that is capable of accepting and displaying a high-definition signal at either 720p, 1080i or 1080p using a component video or digital input, but does not have a built-in HD-capable tuner.
The similar HD ready term in the US to the certification in Europe might falsely imply that a TV from one region works in another (for e.g. HD that differs by frame rate, if not the older non-HD formats); The consensus seems to be the American TVs do not work (fully) with European [HD] broadcast, while European TVs are multi-system (may or may not have or strictly need a US TV tuner, but will support those broadcasts [with an external tuner]).