The Republican presidential nominee, Donald J. Trump, has hired a top executive from Breitbart News, Stephen Bannon, as his campaign’s chief executive, raising expectations that Mr. Trump will adopt the more aggressive style that the site has championed.

So, What Is Breitbart?

The Breitbart News Network, usually just called Breitbart, is a conservative-leaning news website.

It was founded in 2007 by Andrew Breitbart, a former liberal from Los Angeles who became a conservative standard-bearer until his death from heart failure at 43 in 2012.

The site that bears his name comprises about a dozen different verticals that feature original reporting and commentary, including three of its most prominent sites: Big Government, Big Journalism and Big Hollywood. A fourth “Big” site, BigPeace.com, now redirects to Breitbart’s National Security section.

According to SimilarWeb, a web analytics platform, Breitbart’s traffic is comparable to that of Slate and Gawker, and it has received more visitors than either of those two sites over the past several months.