NAVIGATORS:
Navigators in the books are the cornerstone of interstellar trade. By harnessing the power of the Spice, the navigators can bend space/time to make trade and travel possible. The Navigators perform a necessary service that all can respect and few understand. The navigators themselves are actually mutated by the spice into creatures that used to be human, but are now some strange subspecies that no one has ever seen before, save for the members of the Spacing Guild and even they have a hard time ever achieving this. No one is allowed to see a navigator or interact directly with them. all contact must be done through guild agents. If someone were to see a navigator, their shipping priveliges would be immediately revoked and their house would perish almost immediately. Navigators represent the computer nerds in this classification system. The hard-core geeks who have low social skills, but high intelligence and mastery of all things digital.
FREMMEN:
The Fremmen live on Arrakis (the only known planet in the universe where Spice is found). They live in the wastelands of the great desert, banding together in small seich communities for survival. The fremmen are very good at keeping themselves alive and those that they deem worth saving. The fremmen are bombarded by Spice wherever they go. it is in the air they brethe, the food they eat, the water they drink. It is so abundant that by the time a fremmen child turns twelve, their eyes have turned completely blue (no whites). While the Fremmen have a lot of Spice around them, they are not subjected to nearly as much as the Navigators. Therefore, the Fremmen represent the people with more computer knowledge than a lot of people, but not as much as the Navigators. Fremmen are usually found around Navigators asking them when the last time they ate was (in the real world, not the books)
HUMANS:
Normal people. Humans know that Spice is important and that there is no telling its real worth, but that's about all they know. Humans like Spice and try to get ahold of it if they can, but it is not something that they NEED per-se. It is usually left to the Navigators and the Fremmen to know about Spice. Humans can have some knowledge, but usually not too much. humans are the normal people who use computers but only know a few things about them and try not to stray too far from the beaten path. They are more concerned with the struggles between the Great Houses and other such matters.
WATER SELLERS:
also known as Stillsuit Manufacturers. these are humans who are trying to make it on Arrakis but are doing it in ways that they have no real concept of and aren't very good at. these are the people who are blissfully ignorant of ALL things computer and remain that way either through their own stubborn efforts or just that they don't get it and never will