Here is one definition for "alt right" on Wikipedia. I don't have an issue with much of their definition, but their inclusion of Breitbart is a mistake.
Alt-right - Wikipedia
The
alt-right, or
alternative right, is a loosely defined group of
people with
far-rightideologies who reject
mainstream conservatism in favor of
white nationalism.
White supremacist[1] Richard Spencer initially promoted the term in 2010 in reference to a movement centered on
white nationalism, and did so according to the
Associated Pressto disguise overt
racism,
white supremacism, and
neo-Nazism.
[2][3][4] The term drew considerable media attention and controversy during and after the
2016 US presidential election.
[5]
Alt-right
beliefs have been described as
isolationist,
protectionist,
antisemitic, and white supremacist,
[6][7][8] frequently overlapping with
Neo-Nazism,
[9][10][11][12] nativism and
Islamophobia,
[13][14][15][16][17] antifeminism,
misogyny, and
homophobia,
[9][18][19][20][12]right-wing populism,
[21][22] and the
neoreactionary movement.
[6][23] The concept has further been associated with several groups from
American nationalists, neo-
monarchists,
men's rights advocates, and the
2016 presidential campaign of
Donald Trump.
[13][22][23][24][25]
The alt-right has its roots on
Internet websites such as
4chan and
8chan, where anonymous members create and use
Internet memes to express their ideologies.
[6][11][26] It is difficult to tell how much of what people write in these venues is serious and how much is intended to provoke outrage.
[21][27] Members of the alt-right use websites like
Alternative Right,
Twitter,
Breitbart, and
Reddit to convey their message.
[28][29] Alt-right postings generally support the policies of Donald Trump and
Mike Pence [30][31][32][33] and oppose
immigration,
multiculturalism and
political correctness.
[10][18][34]
The alt-right has also had a significant influence on conservative thought in the United States, such as the
Sailer Strategy for winning political support, along with having close ties to the
Trump Administration. It has been listed as a key reason for Trump's win in the 2016 election.
[35][36] The Trump administration includes several figures who are associated with the alt-right, such as former White House Chief Strategist
Steve Bannon.
[37] In 2016, Bannon described Breitbart as "the platform for the alt-right", with the goal of promoting the ideology.
[38]