 Individual images are projected in rapid succession.  In the (movie) theater this is done at 24 frames per second (fps).  On TV (NTSC) this is done at fps.  A frame rate of at least 12 fps is necessary to keep images from appearing jerky.  A frame rate of greater than 70 fps usually does not improve the smoothness.

 A raw image from a 6 megapixel camera has approximately 6 million dots. If this is animated at 30 fps, then the total number of dots is 180 million per second or 10,800,000,000 dots per minute.  If we use 3 bytes per dot this gives 32 billion bytes per minute of video.  A two hour movie would require 4 trillion bytes of data = 45 DVDs = 15 blu-ray disks.

 MPEG-1  Video CDs (popular in Asia), some online video, universal support on computers and DVD players  MPEG-2  DVDs, supported by all DVD players and all computers with DVD drives with the ability to play DVD videos, One of the codecs used in Blu-Ray

 MPEG-4 (part 2)  Internet, storage media. Slightly lower quality than MPEG-2 but smaller size. Will hold the contents of a typical DVD on a CD. DivX, xVid  MPEG-4 (part 10) H.264  The current standard for video compression. Used in Xbox, OS X, iPhone, among others. Very high quality with very small size.  WMV (windows media video)  A series of Codecs from Microsoft that ranges from small enough for dial-up to high enough quality for HiDef video.