Hogwarts was founded by the 4 most notable wizards/witches. Their names were Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw, and Salazar Slytherin. Together they created Hogwarts.

Gryffindor

Gryffindor's traits are courage and chivalry, bravery, and helping others. Their common room is located in Gryffindor Tower. You can only enter if you have the password. The head of house used to be Minerva McGonagall but now it's Neville Longbottom. The House Ghost is Nearly Headless Nick.

Hufflepuff

Hufflepuff's traits are hard-working, patience, fairness, just, loyalty, and modesty. Their common room is in the basement near the kitchen. In order to enter you have to tap barrel two from the bottom middle of the second row in the rhythm of "Helga Hufflepuff" which would make the lid swing open. However, if the wrong lid was tapped or the wrong rhythm was used the intruder would be doused in vinegar and barred access. The Head of House is Pomona Sprout. The House Ghost is the Fat Friar.

Ravenclaw

Ravenclaw's traits are wit, learning, wisdom, acceptance, intelligence, and creativity. Their common room is at the Ravenclaw Tower. You have to pull the bronze knocker then it will ask you a riddle. If you answer it incorrectly you have to wait for someone else to get it right. The Head of House is Filius Flitwick. As for the House Ghost who is the Grey Lady.

Slytherin

Slytherin's traits are resourcefulness, determination, pride, cunning, ambition, and self-preservation. Their common room is in the dungeons. In order to enter you need to a password is required to reveal a passage to the common room. The Head of Hosue is Horace Slughorn. The House Ghost is the Bloody Baron.