I will simplify it, Political campaigns here in the U.S. use "op research" on opponents to dig up dirt. In the primaries, before Trump was the nominee, his (R) opponents did op research with a firm named
Fusion GPS. Once Trump became the candidate the (R)'s
stopped. HOWEVER, the Clinton Campagne picked it up and continued. A retired British MI6 agent named Christopher Steele (on the payroll of our FBI at the time) was used to procure intelligence information from several of his
former contacts in Russia. Steele, working with others, compiled a "dossier" containing wild and unsubstantiated claims about Trump.
* Steele initially "leaked" his work to the press to doom the Trump campaign which failed.
* When the FBI discovered Steele to be the leaker he was fired.
* The DNC or Clinton Campagne initially denied being the source of funding for the dossier.
* Agents of the FBI knowingly and repeatedly used the specious dossier to obtain warrants in our secret FISA courts (failing to tell the court it was paid for by the DNC) to spy on associates of the Trump organization.
* In the aftermath of the bitter defeat Clinton and here sympathizers in the mainstream media continued to advance the conspiracy that the Russians actually conspired with Trump to defeat her when in fact it was the Clinton campaign that effectively conspired with Russian interest to defeat Trump which failed. Political foes continued to press the spurious dossier in an attempt to impeach Trump.
* In an ongoing investigation into the source of the dossier 2 arrests have been made. One a former FBI lawyer who pleaded guilty to altering an email between the CIA and FBI and Russia foreign policy analyst Igor Danchenko who lied about his contacts with DNC operatives.
Ex-FBI lawyer admits to false statement during Russia probe
A former FBI lawyer has pleaded guilty to altering a document related to the secret surveillance of a former Trump campaign adviser during the Russia investigation
Ex-FBI lawyer admits to false statement during Russia probe
LEGAL
Steele dossier source arrested in Durham probe
Researcher Igor Danchenko is charged with five counts of false statements in an inquiry into the origins of the FBI’s Trump-Russia investigation.
Steele dossier source arrested in Durham probe