Earlier socialism was defined as an economic system based on social interest. Rousseau and Proudhon argued for the elimination of private property. Charles Fourier, Robert Owen advocated Utopian socialism, i.e., rich people be given moral values and should share their wealth. Gandhi and Swami Vivekananda were inspired by such ideas. Karl Marx defined socialism as - from each as per his ability, to each as his contribution. He saw it as an intermediate stage between capitalism and communism. Bhagat Singh was a proponent of this revolutionary socialism. I explain all these things.