A tax is a financial levy of charge imposed by the state onto the individuals or organization living in the state. If a tax is not paid, then the individual or organization is punishable under law.
A taxation system is the set of all taxes and the corresponding set of rules applicable related to payment of tax and reimbursement of tax, returns of excess tax paid, fine in case of tax not paid, punishment in case of no tax paid or cheating etc. are the part of taxation system.
In india the various taxes are : income tax, sales tax, corporate tax, customs tax , central excise tax etc. customs tax could be import tax or export tax.
income tax is the tax imposed on net profits earned by companies or salary of an individual , above some limit.
The system of taxes is managed by finance department & ministry. This is revised every year during the budget presentation.