(CNN) With today's heated political rhetoric, you've probably heard politicians or pundits hurl terms that weren't even in the dictionary a few years ago:

Alt-right. "Alt-left." Antifa. The list goes on.

What exactly do they mean? What's the difference between a white nationalist and a white supremacist?

Here's a glossary of phrases spreading through our political vocabulary:

Alt-right

"Alt-right," a self-styled descriptor for many white-rights activists, has become intertwined with the terms white nationalism and white supremacy, said Oren Segal, director of the Anti-Defamation League's Center on Extremism.

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"They're disaffected with mainstream conservative speech, (but) they don't want to be associated with overt white supremacist neo-Nazi groups," University of Oregon professor Randy Blazak said.

"They want to express anti-immigration views, anti-multicultural views, economic protectionism."

The term did not exist until a few years ago, when it started gaining traction after white supremacist Richard Spencer coined it, according to the Anti-Defamation League

Blazak said alt-right activists are typically "moderate-income, working-class white males who are left out of the globalization and ... feel left out of all the progress that's happening."

'Alt-left'

But Segal said "alt-left" is a "made-up term" used by people on the right to "suggest there is a similar movement on the left." But there's no equivalent with the anti-Semitic and bigoted groups that call themselves "alt-right," he said.

"Obviously, there are left-wing extremists, but there is no congruence between the far-left and the alt-right," Segal said.

That's not to say there aren't radical leftists who have engaged in violence. But they generally don't use the term "alt-left."

Antifa

The Antifa isn't a group; it's an ideology that stands for "anti-fascist," said Ryan Lenz of the Southern Poverty Law Center

"They frequently engage in violence to make their point," Lenz said.

He cited a 2012 case in which activists "walked into a high-end restaurant in Chicago where a white supremacist group was eating and literally beat them up with baseball bats."

The term is used to define a broad group of people whose political beliefs lean toward the left -- often the far left -- but do not conform with the Democratic Party platform.

Antifa activists feel the need to get violent because "they believe that elites are controlling the government and the media. So they need to make a statement head-on against the people who they regard as racist," said Brian Levin, director of the Center for the Study of Hate and Extremism at California State University, San Bernardino.

"There's this 'It's going down' mentality and this 'Hit them with your boots' mentality that goes back many decades," he said.

Neo-Nazi

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Neo-Nazis are united by their hatred of Jews, but their antipathy has expanded to include other minorities, gays and even some Christians, according to the Southern Poverty Law Center

Their belief is that Jews are responsible for many social problems, and that Jews control governments, the media and financial institutions, the SPLC says.

The National Alliance is one of the most prominent Neo-Nazi groups in the United States. It calls for the elimination of Jews and other races and promotes the creation of an all-white homeland.

White nationalist

The term white nationalism originated as a euphemism for white supremacy, said Segal of the Anti-Defamation League's Center on Extremism.

At its core, white nationalists want to develop and preserve a white national identity.

White nationalists believe the country "should be built by and for white people," said Mark Potok, senior fellow at the Southern Poverty Law Center.

They "tend to be less about ethnic slurs, less about Nazi slurs, tend to speak more academic language."

But the Ku Klux Klan, neo-Confederates, neo-Nazis, racist skinheads and the Christian Identity can be considered white nationalists, the SPLC said.

White supremacist

White supremacy is the belief that white people are superior to all other races and should therefore dominate society, Segal said.

White supremacists see diversity as a threat. Segal said a popular white supremacist slogan is, "Diversity is a code word for white genocide."

Daryl Johnson, a former counterterrorism expert for the Department of Homeland Security, said recent policies are aligning with the wishes of white supremacists.

"The anti-immigration xenophobia is rising," said Johnson, owner of domestic terror monitoring group DT Analytics.

"US policy is becoming more isolationist -- the building of the (border) wall, the travel ban, mass deportations. These were ideas that I read about 10, 15 years ago on white supremacist message boards. Now they're being put forth as policy."

Black Lives Matter

Black Lives Matter started as a protest slogan and social media hashtag several years ago after the deaths of unarmed black men and women at the hands of police.

White Lives Matter

White Lives Matter is a loosely defined movement founded in 2015, the SPLC says. It calls WLM the "racist response to the Black Lives Matter movement."

Spencer, the white supremacist credited with coining the term "alt-right," was supposed to speak at the event, which was reportedly inspired by the "Unite the Right" rally in Charlottesville.

But Texas A&M canceled the White Lives Matter event, citing safety concerns.

Of course, there's nothing inherently racist in saying "white lives matter" or "all lives matter." But the context is important, Miami Herald columnist Leonard Pitts said.

"An example of avoidance would be when you hear people say 'all lives matter' in response to the claim that 'black lives matter.' Obviously, all lives matter. But that's avoiding the issue," Pitts told CNN.

"... When we talk about racism, we're talking about systematized oppression, and in order to benefit from systematized oppression, you have to have the power."