Questions related to the earning of money (or other capital) within a specified time frame. Topics such as methods to increase income, account for it, track it, analyze it, or disclose it are all appropriate, but discussions of *income tax* should use that tag instead.
Income is the consumption and savings opportunity gained by an entity within a specified time frame, which is generally expressed in monetary terms.
Source: Wikipedia
Note: The entity may be a person, family, corporation, or country as these can be taken from various perspectives. In the first couple of cases this is generally about salary, savings and investments that provide the resources for a person or family to live. On the corporate side, income is part of the accounting that is done.