They are used by the compiler as an aid to compiling the program. They are always written in lower case. In addition to this list of keywords, your compiler may define a few more. If it does, they will be listed in the documentation that came with your compiler. Each of the above keywords will be defined, illustrated, and used in this tutorial.
Any computer program has two entities to consider, the data, and the program.
They are highly dependent on one another and careful planning of both will lead to a well planned and well written program. Unfortunately, it is not possible to study either completely without a good working knowledge of the other. For that reason, this tutorial will jump back and forth between teaching methods of program writing and methods of data definition. Simply follow along and you will have a good understanding of both. Keep in mind that, even though it seems expedient to sometimes jump right into coding the program, time spent planning the data structures will be well spent and the quality of the final program will reflect the original planning.