Many times when we hear the word artifact we think of objects that were used by people in the past and that have a lot of monetary value. While this is true most of the time for archeological objects it is not in the world of high definition television. When talking about HDTV and televisions sets in general an artifact is something very different from what you see in movies such as Indiana Jones. It refers to problems in the picture that happen for different reasons and that are very detrimental to the picture. There are many types of artifacts that can appear in the picture. Some examples are jagged objects sometimes called jaggies, motion artifacts, HDTV Blur and noise which is sometimes referred to as mosquito noise by many members of high definition online communities.
There are many reasons why these distortions can appear in the picture. Some of them such as jagged objects can be introduced by poor signal compression or can be created by a low quality TV set. There are some that are most of the time attributed to a poor quality product such as motion artifacts like tracers while there are others that appear when there are signal problems such as fragmented images and the like.
The only things that people can do in order to minimize the appearance of HDTV artifacts is to choose a quality product, try to improve the signal that is entering the set by moving any antennas around or buying a better one or trying to improve any existing connections. Sometimes unwanted artifacts appear no matter what the consumer does.
High definition looks really impressive but it is still not perfect. Still there is lots of fun to be had with these televisions even if sometimes the picture gets all scrambled and distorted.
More about HDTV here: http://www.faqhdtv.com/.