This document provides an overview of key concepts in the Income Tax Act of 1961 in India. It discusses that the Act applies to all of India and was introduced on April 1, 1962. It defines important terms like gross total income, previous year, assessment year, person, assessee, and ordinary assessee. Gross total income is the aggregate of income under various heads like salary, house property, business or profession. The previous year refers to the financial year preceding the assessment year when taxes are paid.