The term "non-professional rocketry" is so broad that it is typically broken down further in general use. There are four common categories used to describe the sub-groups:

• Model Rocketry is what many of us did as children. The classic model rockets are those made by Estes, Centuri (now defunct) and Quest. Estes and Quest rockets are available in most hobby shops and larger toy stores. These rockets use pre-manufactured, inexpensive, usually black powder motors up to "D" size.
  The rockets generally weigh a few ounces and fly less than 1000 feet high, which allows them to be flown in any open space without special permission.
  Model rockets are usually simple to build and quite safe. People who enjoy model rocketry are generally more interested in rocket design and frequent flying since motors are inexpensive ($1-$4 per flight).
• Mid-Power Rocketry (also Large Model Rocketry) is the next step up in power from model rocketry. These rockets use pre-manufactured, composite ammonium perchlorate motors in the "E" through "G" sizes. The largest manufacturer of mid-power kits is AeroTech, although there are many other companies.
  These rockets also generally weigh under a pound, but fly much higher than model rockets. Rockets which fly above 1000 feet require FAA notification so you will generally be restricted to club launches.
  Mid-power rockets are more demanding to build than model rockets, although many of the materials and building techniques are the same. The motors are a bit more expensive ($4-$15 per flight), but not outrageous.
• High-Power Rocketry encompasses the largest rockets built with commercially manufactured motors and sanctioned by national organizations. The motors used range from "H" through "O" size. The largest manufacturers of high-power kits are Loc/Precision and Public Missiles, Ltd., although there are a few other companies.
  These rockets generally weigh from a few pounds up to a hundred pounds or more and can fly up to 25,000 feet (and even higher). The motors require federal licensing to purchase or posses and can only be flown at organized club launches held in unpopulated areas of large open space.
  High-power rockets are the largest and most challenging rockets which fly on pre-manufactured motors and appeal to those who like large rockets and enjoy the impressive flights with the larger, more powerful and more expensive ($20-$1000) motors. More advanced materials and techniques are required for high-power rockets because of the dramatically more powerful motors.
• Amateur Rocketry (also Experimental Rocketry) is rocketry where the entire rocket is built by the hobbyist, including the motor. Motors can be any size, though generally they tend to cluster in the smaller high-power range. (Note that amateur rocketry is distinguished not by motor size, but by the fact that the hobbyist makes his own motors.)
  Amateur rocketry groups exist, but there are no national organizations which offer insurance and support amateur launches. In some ways, amateur rocketry is less regulated than high-power rocketry, although the FAA requirements are the same. Making your own motors can be dangerous and should not be undertaken lightly.
  Amateur rocketry is appealing to People who either want to do everything themselves or enjoy the process of developing and making their own motors. (Note that making your own motors is rarely a money-saving proposition.)

"Hobby rocketry" is also used to describe model, mid-power and high-power rocketry. Specifically rocketry where the motors are pre-manufactured (as opposed to amateur rocketry).