Attached Link: http://www.turneraudio.com/tech/timecode_primer.html

Here is a link that explains it in detail. Sorry, but I cheated ;)

Quote - In the beginning there was black and white television and it was good sayeth the word. These pictures were broadcast in the United States at a vertical sync of 60 Hz with a frame rate of 30 FPS. When RCA and CBS were developing color television broadcasting one of the prerequisites for the new format was that it be backwards compatible with all the black and white TV's in use at the time. The NTSC (National Television Standards Committee) shifted the vertical sync a measly 0.06 Hz (a 0.1% difference) to 59.94 Hz which gave NTSC color TV the frame rate of 29.97 FPS. So far so good, the broadcasters were happy and so were our prehistoric couch potatoes. In 1956 Ampex produced the first VTR. For years video tape was edited the same as audio tape; manually with a razor blade. While this method worked well with audio, it wasn't nearly as precise given the helical scan of video tape and was certainly not capable of frame accuracy. Ampex refined "electronic editing" in the early 1960's with control track edit systems. In the late 60's time code video tape editing was developed and offered frame accurate edits with each video frame identified with a unique eight digit time stamp of Hours: Minutes: Seconds: Frames. The standards for SMPTE/EBU time code were born in 1969. A committee of folks from the U.S. based Society of Motion Picture and Television Engineers sat down with representatives from the European Broadcast Union. The result was that five different frame rates of time code were agreed upon. The frame rates are; 30, 29.97, 25, 24 and drum roll please, 29.97 drop frame. Some years following the agreed upon frame rates a sixth rate, 30 drop frame was "standardized" by several manufacturers and is included today on most popular field recorders, slates and TC generators. Remember that even though NTSC color television operates at 29.97 FPS, time code readers display an even 30 frames per second. One of the compromises facing the standards committee was that the 29.97 frame rate was 0.1% slower than real time. When the time code display finally reaches one hour (01:00:00:00) the program is actually 108 frames or 0.1% too long. This translates into 3.6 seconds and is enough to make broadcast types very unhappy. The standards committee came up with 29.97 drop frame TC to cope with the difference between real time and the time code count. 29.97 DF code eliminates the first two frames every minute, except for every tenth minute. This results in the loss of 108 frames per hour and the effective resolution between an uneven frame count and real time.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi