Bourgeois socialism or conservative socialism was a term used by Karl Marx and Friedrich Engels in various pieces, including in The Communist Manifesto. Conservative socialism was used as a rebuke by Marx for certain strains of socialism, but it has also been used by proponents of such a system. Conservative socialism and right wing socialism are also used as a descriptor, and in some cases as a pejorative, by free-market conservative and right-libertarian movements and politicians to describe more economically interventionist strands of conservatism.