Gross Total Income is the total of everything you've earned across all five recognised heads of income under Indian tax law — salary, income from house property (like rent), capital gains, profits from business or profession, and income from other sources (like interest or dividends) — added together, before any deductions like Section 80C or 80D are applied.
This figure is an important intermediate step when filing your tax return: you first calculate your Gross Total Income by combining all income sources, then subtract any eligible deductions to arrive at your final Taxable Income, on which your actual tax liability is calculated using the applicable slab rates. Understanding this distinction helps clarify why two people with the same salary can end up with very different final tax bills, depending on their other income sources and deductions.