They were a faction of the Marxist Russian Social Democratic Labour Party founded by Vladimir Lenin and Alexander Bogdanov.
In 1912 they split from the RSDLP and formed their own party. Five years after they took power in Russia overthrowing the republican government created after the abdication of the Tsar a couple of months before. The Bolsheviks lead both the February and October Revolution and became the only ruling class in Soviet Russia and the Soviet Union.
The Bolshevik was a communist regime that was able to defeat the white armies, or the Melsheviks(?) (Sorry can't spell it), who only were able to fight together because they didn't want communism.
The white army was co.mprised of people who still wanted the noble family, those who wanted democracy, and people who just don't like communism, while the boshelviks were communists who wished to place the whole country under their ideology
