Begin at the Beginning

When starting research, it's best to begin with the basics (lower level of Bloom's, so to speak). What is a gear? What kinds are there? These are the basic questions since I know absolutely nothing about gears.

A quick search in a dictionary finds that a gear (as a noun) is a toothed wheel in a machine -- in fact, a mechanism that performs a specific function in a complete machine. Further down on the page the more complete explanation says

"Machine component consisting of a toothed wheel attached to a rotating shaft. Gears operate in pairs, the teeth of one engaging the teeth of a second, to transmit and modify rotary motion and torque. To transmit motion smoothly, the contacting surfaces of gear teeth must be carefully shaped to a specific profile. The smaller of a gear pair is often known as the pinion. If the pinion is on the driving shaft, the pair acts to reduce speed and to amplify torque; if the pinion is on the driven shaft, the pair acts to increase speed and reduce torque."

This sounds pretty simple: a gear is a toothed wheel that works with another one to speed up or reduce the action. In fact, it sounded so simple I get cocky and visited the Kohara Gear Industry Company's online pdf booklet, Introduction to Gears 1st Edition, and YIKES! found out I am so clueless. There is so much math and terminology. Although this booklet will be helpful eventually I'm sure, it is far more complicated than I am ready for at this point. Is there a more simplistic way to learn about movable toy-making without becoming an engineer?