Long Put Option is basically Long on Put on index/underlying stock which is a bearish strategy.
Buy Put option if your view on the Market is Bearish.
Strategy - Bearish
Risk - Limited on to the premium paid
Reward is unlimited
Breakeven is Strike price - premium paid
If the Market is Bearish and crosses break even point, you are in profit.
If the Market is Bullish, you will be in loss.
Eg.
Nifty Currently trading at 16200.
You bought Nifty 16100 PE July 2022 @ 100 premium of 1 lot size (50 contracts )
So, 100*50= 5000 is the premium paid up for Nifty 16100 PE July 2022.
If the Market is Bullish, and ends up in 16300 on expiry date, you risk of losing your capital is limited to 5000 only.
If the Market is Bearish and ends up @15950 on expiry, you will be in profit of 50*50 = 2500 , though it may be even Higher because the premium will be increased on bearish movement.
If Market is @ 16000 on Expiry, that is the breakeven. So there will be no loss and no profit.
So Buying a Put Option is beneficial only in short term .
For 1 point increase in Nifty, delta will decrease. As the contract is near to expire, theta also deceases every day so that the premium decays
*For information about 👉Option Greeks