Why is STT charged?

Could you elaborate on why STT, or Securities Transaction Tax, is imposed? Is it a means to regulate the capital markets and ensure fair play, or does it serve a fiscal purpose for the government? How does STT impact investors and traders in the cryptocurrency and finance sectors? Are there any exemptions or reductions in STT that investors should be aware of? Understanding the rationale behind STT's imposition is crucial for navigating the financial landscape effectively.