The Steele dossier is a collection of documents compiled by former British intelligence officer Christopher Steele. It contains unverified allegations about Donald Trump and his connections to Russia, including claims of misconduct and potential collusion during the 2016 U.S. presidential election. The dossier was initially commissioned by a political research firm, Fusion GPS, to investigate Trump's ties to Russia. It became a focal point in discussions about election interference and was used in various investigations, including those led by the FBI and Robert Mueller.