Generators give power to other components. Weapons allow the object to blow stuff up. Radios allow the object to communicate with other objects. Shielding protects other components. Engines give the object the ability to move.
Tools provide various specific functions.
Engines must be placed in the lower section. Radios must be placed in the upper section. Weapons cannot be placed in the lower section. Once an object is created, the object's code file begins to load. When the file finishes loading, the code begins to run, and it can execute commands to add components, explore the environment, and build new objects.