Alright, let me make something clear. I don't own Dune. I am an avid reader, but Dune belongs to Frank Herbert and his son. I'm just making my own story in his universe. Everything in here except for certain characters, planets, events and philosophies belong to the Herbert Estate. So, don't sue me, because I'm too poor. And then, I'll go ahead and beat your ass legally on Jerry Springer for suing me. Here's a basic intro:

House Cepeda: a House Minor that has been loyal to the Atreides since the Battle of Corrin. My series of chapters and short stories are based on their story. They belong to me!
House Atreides: a Great House that saved humanity from oppression against the living machines at the Battle of Corrin.

House Harkonnen: a Great House that is the sworn enemies of the Atreides. Harkonnens are sadistic and evil, compared to Atreides honor and loyalty. They were banished by the Atreides due to their cowardice at Corrin, and only recently returned to power.
Butlerian Jihad: a fierce crusade started by Serena Butler, it culminated in the Battle of Corrin, which was humanity's victory against the living machines.
House Corrino: the ruling House of the Imperium. The head generals of the Battle of Corrin, they take their name from that victory. First leg of the political tripod that makes up the Imperium.
Imperial Sardaukar: the soldier-fanatics of House Corrino. One Sardaukar can take on ten ordinary conscripts.

Landsraad: parliament made up of the Great and Minor Houses of the Imperium. Second leg of the political tripod that makes up the Imperium.
Spacing Guild: group that has a monopoly on banking and space travel. Use prescient Navigators to see a way across foldspace. Third leg of the political tripod that makes up the Imperium.

CHOAM: main company of the Imperium, handles everything from dunkey dung to spice mélange to Ixian technology. CHOAM directorships are the key to Imperium political power.
Arrakis: home of the spice mélange and the Fremen. Fierce desert planet.
Melange: spice found only on Arrakis. Melange has true geriatric properties. It also grants limited prescience and is very addictive.

Shield: force field that repels projectiles and blades except for a slow blade weapon. Lasguns that intersect shields produce clean atomics.
Great Convention: body of laws and agreements that forbids certain actions. Chief among them is the use of atomics, which are maintained by all the Great Houses of the Landsraad in special reserve.

Ix: secretive planet that produces the most cutting edge technology. Ixian products are much desired in the Imperium.
Richese: a beaten House and planet, it mainly produces cheap copies of Ixian technology.