They're the most dominant terms used to describe more than 65 million people who make up nearly 20% of the U.S. population: Hispanic and Latino.

They're two simple terms with complex roots that are often used interchangeably. But as Stella Rouse explains, the rich history behind the terms Hispanic and Latino isn't simple at all.

"It's not a simple community," she told Scripps News. "It's very diverse, very heterogeneous."

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Hispanic refers to a person with ancestry from a country where the primary language is Spanish.

In the 1970s the federal government adopted the use of the term Hispanic in a move to help allocate federal dollars and resources. But it's a word that's been resisted and a source of debate.

"It's very much a government label that was imposed on the community," Rouse explained. "And of course, you know, often times the relationship of Latinos and the Latino community with the government have not always been great."

Rouse was born in Colombia and is now the director of the Hispanic Research Center at Arizona State University. She says that for some people, Latino simply feels more organic.

"That's a word that's come from, you know, from the societies of people that come from Latin America, who speak Spanish, who have that common origin," said Rouse.

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Latino is short for Latinoamericano. It refers to someone with origins from anywhere Latin America, including Mexico, South America, Central America, and the Caribbean.

To increase inclusiveness in the early 21st century, the term Latinx emerged as a gender-neutral alternative to Hispanic and Latino or Latina.

While the word experienced the spotlight, Mark Hugo Lopez with the race and ethnicity research division at the Pew Research Center says that Latinx failed to connect with Spanish speakers and gain widespread usage.

"You often times will find, for example, that Spanish speakers will say, 'Well that's something that English speakers created. That's not, how do you pronounce x in, we don't use it in Spanish,'" explained Lopez. "And so there was this little bit of a sense that it was also American cultural imperialism."

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According to a recent Pew Research Center survey, awareness for the term Latinx has grown, but just 4% of Latino adults say they have used the word to describe themselves. As a replacement, Latine surfaced.

"So, Latine is from Latin America," explained Lopez. "And it's something that you can conjugate in Spanish... and you can pronounce it in Spanish."

Experts say the best way to determine the use of these words is to never assume, and simply ask the person you're speaking to how they identify.