非专家， 就定义再瞎掰两句

The act of placing capital into a project or business with the intent of making a profit on the initial placing of capital. An investment may involve the extension of a loan or line of credit, which entitles one to repayment with interest, or it may involve buying an ownership stake in a business, with the hope that the business will become profitable. Investing may also involve buying a particular asset with the intent to resell it later for a higher price. Many types of investing exist, and each is subject to greater or lesser regulation in the jurisdiction in which it takes place. Legally, investing requires the existence and protection of individual property rights. Investing wisely requires a combination of astuteness, knowledge of the market, and timing.

由此可见，income from cash flow or Sch C or E is earned income while profits from appreciation by selling or Sch D are investment income.

my $0.02.