Motels, hotels and resorts in the U.S. are awarded stars to designate their overall quality, starting at one star on the low end and climbing to five stars at the high end. But what do these stars mean, and how did they come about?

The hotel-star system was introduced in 1958 by the Mobil Travel Guide to promote American road trips. Today, the Forbes Travel Guide employs incognito inspectors to assess the standards in properties across the country. Four-star and five-star results, the only ones they focus on, are published annually in the Forbes Travel Guide.

But they’re certainly not the only ones awarding stars. (Or, in their words “verifying luxury.”) Travel websites and metasearch engines like Expedia and Kayak and Hotels.com rank properties according to their own subjective requirements. However, one site’s four-star hotel could be a mere three-star on their competitor’s website. Add in each website’s crowdsourced user ratings and things get even more ambiguous.

And just when your head was spinning with stars, let’s add some diamonds to the equation. The American Automobile Association (AAA) Diamond awards diamonds in a way that’s similar to stars for hotels, although the criteria are generally a bit tougher. They employ full-time anonymous inspectors to assess properties across the country. Properties are awarded one diamond for budget-oriented hotels and motels providing no-frills lodging, two diamonds for clean and basic accommodations that are affordable, and three diamonds for a place that's moderately priced, but comfortable, with some amenities. Four diamonds are awarded to hotels that are "refined and stylish, providing upscale physical attributes, extensive amenities and a high degree of hospitality, service and attention to detail." The AAA five-diamond award is so rare that it is generally bestowed upon only .04 percent of the 27,000 hotels inspected. To qualify, a five-diamond hotel must have "ultimate luxury, sophistication and comfort with extraordinary physical attributes, meticulous personalized service, extensive amenities and impeccable standards of excellence."

With all these different rating systems, and fellow travelers voicing their own opinions, it can be tough to compare one lodging option to another. Though the rating criteria vary widely, here’s a general interpretation of the hotel star system in the U.S:

One Star: A property has no frills and only offers basic accommodations. It’s a place to sleep, and that’s pretty much it. You might have to share a bathroom.

Two Star: These are also low on frills, but a bit more comfortable.

Three Star: These accommodations ordinarily have some extra amenities and provide quality service.

Four Star: These hotels generally provide upscale quality and extraordinary comfort.

Five Star: These hotels deliver flawless guest services in a state-of-the-art facility. Expect large luxurious rooms, premium dining options and personalized service, with virtually no detail overlooked.