Each Hogwarts house is known for a few specific qualities, but the people in each house possess qualities that fit in each of the other houses, as well. The right combination of certain qualities could land you in one house even if it seems like you belong in another (see: Hermione); furthermore, it's the way you choose to use certain qualities that set you apart from students in other houses.
Which gives me the perfect opportunity to break down each of the houses according to one trait: boldness.
Let's start with the obvious, shall we? During Harry's 4th year, the Sorting Hat says it flat out: "Bold Gryffindor, from wild moor." In Muggle terms, the Gryffindors are the jocks of Hogwarts: cocky, daring, more than willing to break the rules. But they're also chivalrous and brave, basically making them the coolest house at Hogwarts.
Ravenclaw is where "those with wit and learning, will always find their kind." They use their boldness to fuel their creativity. As pointed out in the Ravenclaw welcome letter on Pottermore, Ravenclaws "are the most individual—some might even call them eccentrics. But geniuses are often out of step with ordinary folk, and unlike some other houses we could name, we think you've got the right to wear what you like, believe what you want, and say what you feel. We aren't put off by people who march to a different tune." Proud Ravenclaw, right here.
Slytherins are willing to do whatever it takes to get what they want. This doesn't necessarily make them evil; it just means they're ambitious. While a Ravenclaw will go to untold lengths to find the answer to a perplexing question, Slytherins will chase their dreams just as far. They tend to be much more subtle about how they go about achieving their goals (just look at Voldemort—he was a sneak through and through), which is one of several reasons why I think I'd be a Slytherin if I weren't a Ravenclaw.
Hufflepuffs get a bad rap for being pushovers, but when faced with a moral battle, I have no doubt that the Puffs would win. They are extremely loyal, and are far more concerned with welcoming people with open arms than worrying about what people think about them. Theirs is a quiet strength, but don't forget that when the moment of truth comes, they'll be a second behind the Gryffindors to charge boldly forward. (And they're only a second because they're more likely to think before they act. I can't say the same for Gryffindors.)
This is a part of a 31-day series on bold living. Harry Potter references have somehow found their way into several of these posts. I'm not obsessed or anything.