Sir I generally want some knowledge on stt that why any company should impose it over a trader even after paying a lot of taxes which I think was not helpful to save some income tax.
STT is imposed by Central Government not by companies.
If you earn 100 in stock trading you will get 30 and remaining will go as taxes and charges.
And this 30 if you spend for your house hold expenses another 5 will go as taxes.
What ultimately you get is just 25.
This is Not the fault of Government but people who are not paying Income tax.
Only 2% people pay Income tax and remaining 98 % eating for free. For life.
Like @haribabu mentioned, STT is levied by the central govt and not by companies. Check this wiki link to know about STT - https://en.wikipedia.org/wiki/Securities_Transaction_Tax
Understanding STT is absolutely essential when you are trading options. I’d suggest you read up this blog post before venturing into options trading - http://zerodha.com/z-connect/queries/stock-and-fo-queries/stt-options-nse-bse-mcx-sx