Definition of Tax :
The term Taxation or Tax is comes from Latin word "Taxatio" which means "Payable Quantam an Estimate". Tax is a compulsory levy upon a person.
According to Taylor, taxes are the compulsory payments to the Govt. without expectation of direct benefit to the tax payer. So we can Say that, tax is an amount of money that compulsory pay to the Govt. It is the expense of the assesses. On the other hand it is the revenue of the Govt.In every country about 80% of total Govt. revenue comes from Tax.
Characteristics of Tax : i) It is a compulsory levy under taxing act. ii) Tax payer can't get benefited direct or quid qua pro (proportionally get benefited) service for payment of tax iii) It is a price that pay to the Govt. for living in a civilized society iv) It must be a fixed rate v) It is the way for utility producing vi) It helps to develop the economy

Principles / Canons of taxation :
Adam Smith gave four principles of taxation which is called "Canons of Taxation" and those are following : i) Canon of Equality ii) Canon of Certainty iii) Canon of Convenience iv) Canon of Economy

Some other writers prescribed some other principles/ Canons which are below : v) Canon of Productivity vi) Canon of Diversity vii) Canon of Simplicity viii) Canon of Flexibility ix) Canon of Social objectives x) Canon of Functional Efficiency

Classification of Tax : Tax can be classified into different types based on different angles, which are showing below :
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Definition of Assessee :
Generally tax payer called assessee. Assessee is the person on whom tax is levied to pay to the Govt.
According to income tax ordinance 1984, under section 2(7) - Assessee means a person by whom any tax or other sum of money is payable under this ordinance and includes - a) Person against