How much amount is deducted (at source maybe) as a contribution towards provident fund??

As you’ll would have guessed, I really don’t know a lot about salary deductions and contributions. I will really appreciate if someone can enlighten with the way the salary works in India? what sections/heading are people paid under? Which of those fields are taxable? How much gets deducted at source and for what reason? What exactly is a provident fund or public provident fund? How much tax is deducted under professional tax?