This guide introduces the common types and categories provided by libaldor, and presupposes some familiarity with programming in ALDOR. If you are unfamiliar with ALDOR, then after installing libaldor, go through the tutorial aldorlib/tutorial/tutorial.ps, which will familiarize you both with ALDOR and libaldor. libaldor provides basic categories and types in 3 areas: arithmetic, data structures and input/output. Figure 1 shows the general category hierarchy in those areas and a few of the types provided, while Figure 2 shows the category hierarchy for data structures. Note that all the category names end with the word Type.