Income refers to earnings from labor or capital investments, including savings and the value of personal consumption. It includes gains from business transactions where sale amounts exceed related costs. Income is distinguished from other terms: capital refers to the original investment or funds used to generate income; revenue is funds received by the government from taxes or donations; receipts include both capital and earnings while income excludes capital invested and costs. Nontaxable income is excluded from taxation by law while taxable income is the amount subject to tax rates under law.