Humanity created different methods for sharing information. One of the first forms of sharing information and knowledge were images. In the beginning, the process of sharing was relying on static appearances. With the invention of moving pictures by Eadweard Muybridge in the first part of 1870s, this exchange and sharing gained a new quality. Now it was possible to show and preserve motion too. Since that time, technology has changed rapidly. The latest discoveries and improvements from the point of view of technology use computer and IT technologies extensively. Today it is possible for everybody to create and record movies by themselves using affordable and convenient technological devices.
Also the process of sharing evolved rapidly and become cheaper and cheaper. We are now able to record some movies and share them through the Internet or other carriers in real time or near real time. However, this also creates serious problems due to the huge volume of data to be sent through the data lines. Therefore, research has concentrated on methods to decrease the data volume without losing the quality. One way to do that is to create effective CODECs. A major drawback of moving pictures is the motion itself. CODECs have to minimize the size of videos without paying the price of quality losses but have also to reduce the computational complexity. Both of these requirements can be achieved with a solid knowledge of motion estimation among others. This paper gives a general overview and survey of some existing and important approaches without the claim of having a complete overview of the field.