There are multiple ways in which you can use option chain for trading. Some of the ways are -
To know the Support/Resistance of the underlying based on OI.
Check the OTM contracts that have the highest OI for both Call and Puts. The strike price with highest OI for OTM Call options will act as resistance for the underlying asset.
The strike price with highest OI for OTM Put options will act as support for the underlying asset.
To check the day change in LTP and OI to check if the price change is due to creation of new positions or squaring off existing positions.
If the LTP has increased with the increase in OI, then it means that new buy positions have been created that has increased the price.
If the LTP has increased with decrease in OI, then it means that existing short positions have been squared off that has increased the price.
If the LTP has decreased with the increase in OI, then it means that short positions are being created for
To create a favorable strategy based on option greeks.
For example, to create a Delta neutral strategy in which you are not sure about the direction of the market but want to benefit from the time decay of option contracts, sell a Call option contract and Put option contract with the same delta values. This will nullify the effect of price change of the underlying, so that you can gain from time decay of option premium.