If you are a salaried person, your salary from your employer will be treated as income. On the other hand for a businessman, the net profit will be considered as income.
In all there are five heads for income as follows:
Property rental income
Income from business/profession: This applies for entrepreneurs and small business people who don't get a regular salary income. Some examples are doctors, lawyers, etc
Capital gains such as profit from sale of house, land, gold, etc
Income from other sources such as interest received on bank deposits, winnings from lotteries or game shows, etc.