Here are some key features of options contracts

• Expiration Date: Options have a specific expiration date, after which the contract is no longer valid. In India index options like NIFTY, BANKNIFTY, FINNIFTY, MIDCPNIFTY, SENSEX, etc have a weekly expiry while stock options have a monthly expiry.
• Strike Price: The strike price is the price at which the underlying asset can be bought(in case of call options) or sold(in case of put options) when the option is exercised. For example, if the strike price for a NIFTY contract is 20000 then you can exercise a call option only if the NIFTY index trades above 20000.
• Premium: The buyer pays a premium to the seller for the option. This premium is the cost of obtaining the right to buy (in the case of a call option) or sell (in the case of a put option) the underlying asset. 
• Exercise: The buyer of an option can choose to exercise the option if it is favourable, while the seller is obligated to fulfill the terms if the buyer decides to exercise. When call options are exercised you can buy the from the option writer at the strike price of the contract, while in the case of put options, you can sell the shares to the option writer at the strike price of the contract.
• American vs. European Options: American options can be exercised at any time before or at the expiration date, while European options can only be exercised at the expiration date. 

In Indian markets all option contracts are European, hence you may see PE written against put options which is short for “Put European” and CE written for call options which is short for “Call European”.