The ubiquitous green internet amphibian known as Pepe the Frog has been added to the Anti-Defamation League's database of hate symbols. It's yet another sign that neo-Nazi and white nationalist propaganda is proliferating online.

The Anti-Defamation League's hate symbols database is crowded with acronyms and photos of tattooed hate symbols, but the group has recently decided to look to the internet to more accurately track the spread of hate messages.

"Our hate symbol database has sort of traditionally dealt with hate symbols that people might come in contact with in the street or on the ground," Oren Segal, director of Anti-Defamation League's Center on Extremism, told Mashable. "We realize this year that more people are likely to come across hate symbols every day on their phones or online than necessarily in their neighborhood."

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The addition of Pepe the Frog to the hate database is somewhat new for the Anti-Defamation League, but not without precedent.

Earlier this year, the group added the (((echo))) symbol, which is used by anti-Semites to identify others as Jewish.

The echo's origins come from a podcast aired in 2014 in which the hosts dub Jewish names with an echo-effect. The translation of this echo to text took off earlier this year, so much that many Twitter users who are not anti-Semites began to use parentheses as a way to counter the anti-Semitic message.

The proliferation of Pepe and the echo symbol in many ways mirrors the recent proliferation of white nationalist and neo-Nazi activity on social media.

Pepe the Frog didn't start out as an anti-Semitic meme, but internet users in certain corners of sites such as 4chan, 8chan and Reddit warped the frog into a symbol that promotes "anti-Jewish, bigoted and offensive ideas," according to the Anti-Defamation League's news release. Those ideas took off on Twitter as well as other social networks.

The Southern Poverty Law Center describes the growth of the modern American white nationalist movement -- often referred to as the loosely-defined and Pepe-loving "alt-right" -- in much the same way.

"The general population of the alt-right is composed, by and large, of anonymous youths who were exposed to the movement’s ideas through online message boards like 4chan and 8chan’s /pol/ and Internet platforms like Reddit and Twitter," the The Southern Poverty Law Center says.

And, like the emergence of Pepe as racist/anti-Semitic meme, the online emergence of the alt-right is also recent. Since 2012, "major American white nationalist movements on Twitter" have gained 22,000 followers, "an increase of about 600 percent," according to a recent study of white nationalism online.

That boost in numbers comes partially due to "organized social media activism" and "organic growth in the adoption of social media by people interested in white nationalism," according to the study.

In addition to Pepe the Frog, one of the alt-right's favorite topics of conversation is Republican presidential nominee Donald Trump. In alt-right circles of the internet, talk of Trump has become as ubiquitous as their favorite amphibian.

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