There are two types of taxes direct taxes and indirect taxes,
(i) Direct Tax:
(1) If a tax levied on the income or wealth of a person and is paid by that person or his office directly to the Government, it is called direct tax.
(2) E.g: Income tax, wealth tax, capital gain tax, etc.
(ii) Indirect Tax:
(1) If tax is levied on the goods or services of a person (seller), it is collected from the buyers and is paid by seller to the Government, it is called indirect tax.
(2) E.g. GST

Out of Gross Total Income, Income tax Act, 1961 allows certain deductions under section 80. After allowing these deductions the figure which we arrive at is called 'Total Income' and on this figure tax liability is computed at the prescribed rates.

(i) Any rent or revenue derived from land which is situated in India and is used for agricultural purpose.
(ii) Agricultural income is fully exempted from tax u/s 10(1) and as such does not form part of total income.

These five heads are :
(i) Income from salaries (sections 15-17) 
(ii) Income from House Property (sections 22-27)
(iii) Income from 'Profits and gains of Business or Profession' (sections 28-44)
(iv) Income from capital gains (section 45-55) and
(v) Income from other sources (section 56-59)

Income aggregated after adjusting past and present losses and the total so arrived at is known as 'Gross Total Income'.