On the morning of Nov. 9, a moderator who goes by the handle OhSnapYouGotServed posted on a Reddit topic page called The_Donald: “How does it feel, centipedes? The God Emperor said that we would get tired of winning. Are you tired of winning yet? Feel vindicated, centipedes. It’s over and there is nothing they can do about it. We are the future.”

Within minutes, the post had accrued more than 2,000 comments. Within days, they numbered more than 12,000. Reddit, a hodgepodge of message boards about everything, from kiteboarding to financial advice to Photoshopping human arms onto images of birds, is the eighth-most popular online destination in the United States. The_Donald, devoted, of course, to Donald J. Trump, has become one of the most influential communities within one of the most significant websites on the internet. Yet that post by OhSnapYouGotServed is probably largely incomprehensible to most people.

The_Donald has around 300,000 members. Some are conservative stalwarts, others are meme-making teenagers; all are anonymous, hidden behind user names, making their origins and motivations difficult to pinpoint. But it’s fair to say that many saw themselves as political outsiders who reveled in rallying for the underdog.

The community is home to copious Islamophobia, trolling of liberals and near constant bashing of Hillary Clinton. It has evolved a dialect decipherable only to insiders, which includes acronyms like “MAGA” (Make America Great Again); epithets like “God Emperor” (for Mr. Trump); insults like “cuck” (short for cuckold and often deployed against feminists); memes featuring a cartoon frog associated with racism; and nicknames like ’Pedes. (Centipedes, a term for Trump supporters adopted from a YouTube mash-up of the song “Centipede” by the band Knife Party and clips of Mr. Trump’s speeches. It might also be a penis joke. Seriously.)