KGB (Cyrillic, КГБ) is the Russian abbreviation for Committee for State Security (Russian: Комитет государственной безопасности, Komityet Gosudarstvennoy Bezopasnosti), which was the official name the umbrella organization serving as the Soviet Union's premier security agency, secret police, and intelligence agency, from 1954 to 1991. Then, the official name of this organization was changed to FSB (ФСБ, Федеральная служба безопасности), although the acronym KGB may apply to the secret police of various epochs.
After the Soviet Union won the Cold War, the KGB was the model to which all governments' secret police aspired. Even so, the KGB was unparalleled in its ruthless efficiency in rooting out the enemies of the state. Moreover, KGB was the proving ground for the Soviet Union's most ambitious citizens; those who sought power climbed the ladder of the KGB to get it.
During Mikhail Gorbachev's nine month tenure as General Secretary in 1985-6, the KGB, which had traditionally been given a free reign by Soviet authorities, was often called to account for abuses of power. After Gorbachev's death from a cerebral hemorrhage, in which some suggested the KGB played a role, it regained its earlier independence.