You are asking about a huge topic - what is it you really need? What type of taxes are you studying? What time period are you considering? Do you want facts that support the need for taxes, the reasons for different types of taxes, why taxes have changed over the years? Are you supposed to be forming your own opinion about taxes?
Taxes have existed, in one form or another, for as long as people have come together and created systems of shared responsibility for group living. Expenses for the running of the government have been divided up among the residents and paid through the assessment of taxes since ancient times. Taxes may be direct, like income tax, or indirect, as with a sales tax added to the cost of an item. Taxes may be uniform, when everyone pays the same amount, or progressive, using a scaled system of increments to assess higher taxes upon those with greater assets.
Over time, the use of taxes has been expanded to pay for many things not included directly with governmental functions. In addition to financing police, construction of highways, and air traffic controllers, taxes also are now used to pay for health care, development of natural resources, and building libraries.