Income redistribution is the act or government policy of transferring wealth from richer individuals to poorer individuals. It takes two forms: voluntary redistribution (otherwise known as charity), and compulsory redistribution.
Some conservatives (such as Ayn Rand) oppose most forms of redistribution, believing that a person should only receive in income what they are able to earn through the markets. They believe that charity does harm to the giver (by depriving him of what he earned), to the receiver (by not encouraging him to earn his sustenance), and to society as a whole (by taking resources away from those who have shown themselves able to create employment for others, and giving it to prodigals.
Other conservatives favor voluntary redistribution through charities, but oppose compulsory redistribution, which they see as an unjust interference with private property rights.
Liberals generally support both forms of income redistribution. Their position is premised on an egalitarian view of economic justice, that it is unjust for individuals to have grossly different access to economic resources. Because market systems can at times create these inequalities, and because of their belief that individual charitable giving cannot be relied upon to counter these inequalities, liberals tend to advocate some degree of compulsary redistribution of resources as necessary.
Examples of government programs performing compulsory income redistribution include welfare and progressive taxation.