TL;DR: A call option gives you the right to buy an underlying asset at a fixed price; a put option gives you the right to sell. Both are derivatives — financial instruments that derive their value from the price of another asset. Understanding the terminology behind puts and calls, from strike price and premium to the Greeks, is the foundation every options strategy rests on.
Key Takeaways
- A call option is the right to buy, and a put option is the right to sell, at a predetermined strike price before expiration.
- Options offer leverage — the ability to magnify the value of the premium you pay — but leverage comes with the risk of significant losses.
- Every option premium has two components: intrinsic value (how far it is in the money) and extrinsic value (time and volatility premium).
- The Greeks — delta, gamma, theta, vega — quantify how an option's price responds to changes in the underlying stock, time, and volatility.
- Learning definitions is step one; applying them through strategies like covered calls, credit spreads, and cash-secured puts is where edge is built.
What is a call option?
A call option is a contract that gives the purchaser the right, but not the obligation, to buy shares of an underlying asset at a fixed price (the strike price) by a set date (the expiration). The seller, also known as the writer, accepts the obligation to sell shares if the contract is assigned.
Traders buy calls when they expect the underlying to rise. If the stock climbs above the strike price by more than the premium paid, the call buyer profits. If the stock stays flat or falls, the most the buyer can lose is the premium they paid for the contract.
Call options also serve as hedging tools and income generators. Selling covered calls against shares you already own is one of the most popular income strategies in options trading — you collect premium in exchange for capping your upside. For a deeper walkthrough, see the covered calls income strategy guide.
What is a put option?
A put option is the mirror image of a call. It gives the purchaser the right, but not the obligation, to sell shares at the strike price by expiration. The seller of the put accepts the obligation to buy shares if the contract is assigned.
Put buyers profit when the underlying falls below the strike price by more than the premium paid. The maximum loss for a put buyer is limited to the premium — a meaningful advantage over shorting stock, where losses are theoretically unlimited.
Puts are also the backbone of portfolio protection. Buying a put on a stock you own is known as a protective put: it sets a floor under your downside. If the stock drops, the put gains value to offset your share losses. This functions as an insurance policy on your equity position. If you are interested in selling puts for income rather than buying them for protection, the cash-secured puts guide breaks down the mechanics.
How do puts and calls compare?
The table below lays out the core differences between call and put options side by side. Both are derivatives whose value comes from the price of an underlying asset, but they point in opposite directions.
| Feature | Call Option | Put Option |
|---|---|---|
| Right granted | Buy shares at the strike price | Sell shares at the strike price |
| Buyer profits when | Underlying rises above strike + premium | Underlying falls below strike − premium |
| Seller's obligation | Sell shares if assigned | Buy shares if assigned |
| Maximum buyer loss | Premium paid | Premium paid |
| Common use | Bullish speculation, covered calls | Bearish speculation, portfolio hedging |
| Sentiment signal | Bullish | Bearish |
U.S. investors can trade options on a wide range of financial products — from individual stocks and ETFs to indexes, foreign currencies, and more. The mechanics of calls and puts remain the same regardless of the underlying asset class.
What is the strike price?
The strike price, also called the exercise price, is the fixed price at which the option holder can buy (for calls) or sell (for puts) the underlying asset. It is the anchor of every options contract and the reference point for determining whether a trade is profitable.
When you look at an options chain, you will see a ladder of strike prices above and below the current stock price. The relationship between the strike price and the current stock price determines whether an option is in the money, at the money, or out of the money — terms defined in a later section.
Choosing the right strike price involves balancing cost against probability. Lower-strike calls and higher-strike puts cost more because they are closer to (or already in) the money, but they carry a higher probability of expiring with value. Further out-of-the-money strikes are cheaper but more likely to expire worthless.
What does premium mean in options?
The premium is the price the buyer pays to own the option contract. A call priced at $3.50 would cost the option buyer $350, because standard equity options represent 100 shares per contract [1]. The premium is the buyer's maximum risk on a long option: if the option expires worthless, that is the full extent of their loss.
Premiums are driven by two components: intrinsic value and extrinsic value.
Intrinsic value is the portion of the premium that reflects how far an option is currently in the money. For a put option, intrinsic value equals the strike price minus the security price when that difference is positive. For a call, intrinsic value equals the stock price minus the strike price when positive. An out-of-the-money option has zero intrinsic value — its premium is pure extrinsic value.
Extrinsic value, sometimes called time value, is everything in the premium beyond intrinsic value. It is driven by two forces: the time remaining until expiration and implied volatility. The more time left and the higher the expected volatility, the more extrinsic value the option carries. This is why options lose value as expiration approaches — a process called theta decay. For practical strategies around selling premium and capturing that decay, see selling premium and theta decay.
What do ITM, ATM, and OTM mean?
These three abbreviations describe an option's relationship to the current stock price. They determine how much intrinsic value an option carries and how aggressively its price moves.
In the money (ITM): A call is ITM when the stock price is above the strike price. A put is ITM when the stock price is below the strike price. ITM options have intrinsic value and a higher delta, meaning they track the underlying more closely.
At the money (ATM): The stock price is at or very near the strike price. ATM options have no meaningful intrinsic value but typically carry the most extrinsic value (time premium) of any strike at the same expiration. They are also the most sensitive to changes in implied volatility.
Out of the money (OTM): A call is OTM when the stock price is below the strike. A put is OTM when the stock price is above the strike. OTM options are pure extrinsic value — they will expire worthless unless the stock moves favorably before expiration. With long options, investors may lose the entire amount invested.
What are expiration and exercise?
Expiration is the final date on which the option can be exercised. After that date, the contract ceases to exist. Most listed equity options in the United States are American-style, meaning they can be exercised at any time up to and including the expiration date. Some index options and other specialized contracts are European-style, meaning they can only be exercised at maturity.
Exercise is the act of using your right under the option contract. When a call holder exercises, they buy shares at the strike price. When a put holder exercises, they sell shares at the strike price.
The flip side of exercise is assignment. When an option holder exercises, the seller is assigned — their brokerage firm requires them to fulfill the contract. A call writer who is assigned must deliver shares at the strike price. A put writer who is assigned must purchase shares at the strike price.
Most traders never exercise their options. Instead, they close the position by selling the option back to the market before expiration, capturing or cutting the change in premium. Understanding assignment matters most for sellers of options, who must be prepared to fulfill the obligation at any time for American-style contracts. If you are selling puts specifically, the cash-secured puts guide explains how to manage assignment risk.
What are the options Greeks?
The Greeks are risk measures that quantify how sensitive an option's price is to various factors. They are essential for understanding how a position will behave as market conditions shift. For a thorough breakdown, see the complete guide to options Greeks.
Delta measures the amount an option price is expected to change based on a one-dollar change in the underlying stock. A call with a high delta moves nearly in lockstep with the stock. A put carries a negative delta, reflecting its inverse relationship to the underlying. Delta also serves as a rough proxy for the probability that an option will expire in the money.
Gamma measures the rate of change in an option's delta based on a one-dollar change in the price of the underlying stock. High gamma means delta itself is shifting quickly — something that matters enormously in fast-moving markets and is the force behind gamma squeezes. Gamma is highest for at-the-money options near expiration, which is why 0DTE trading requires especially tight risk controls.
Theta measures the rate at which an option loses value as time passes, all else being equal. This is time decay, and it accelerates as expiration approaches. Theta is the enemy of option buyers and the ally of option sellers.
Vega measures sensitivity to changes in implied volatility. When implied volatility rises, option premiums increase (all else equal), and when it falls, premiums shrink. Understanding vega is critical for trading around events like earnings, where IV crush can destroy premium overnight even if you get the direction right.
What is implied volatility and why does it matter?
Implied volatility (IV) is the market's forecast of how much the underlying will move over the life of the option. It is embedded in the option's price and is the single most important driver of extrinsic value.
Over the last 94 years, the S&P 500 has moved around its average returns by roughly 19% — what is known as the historic volatility of the index [2]. Implied volatility is forward-looking: it reflects what traders expect volatility to be going forward, not what it has been in the past. When fear spikes, IV rises and options premiums swell. When markets are calm, IV contracts and premiums shrink.
The practical consequence is straightforward. Buying options when IV is high means paying up for inflated extrinsic value. If IV drops after your purchase — even if the stock moves in your favor — the option can lose value. This dynamic, often called IV crush, separates profitable options traders from the rest. For strategies that exploit volatility swings, see the straddles and strangles guide.
How do put and call strategies combine?
Calls and puts are not just standalone trades. They are building blocks for strategies that let traders define their risk and reward with precision.
Spreads involve buying and selling options of the same type — both calls or both puts — at different strike prices or expirations. A bull call spread buys a lower-strike call and sells a higher-strike call, reducing cost and capping both risk and reward. A bear put spread does the same with puts. See the credit spreads vs. debit spreads breakdown for a detailed comparison.
Straddles and strangles combine a call and a put to profit from large moves in either direction. A straddle uses the same strike price for both legs; a strangle uses different strikes. These are volatility plays — you do not need to predict direction, just magnitude.
The wheel strategy rotates between selling cash-secured puts and covered calls, collecting premium at each step. It is one of the most popular systematic income strategies for traders who are comfortable owning the underlying stock. The wheel strategy complete guide walks through every rotation.
Options strategies range from relatively low risk to very high risk. The right strategy depends on your market outlook, risk tolerance, and account size. Trading options requires specific approval from your brokerage firm, and each approval level unlocks different strategies based on complexity and risk.
Why This Matters
Options trading volume has grown dramatically as brokerages have eliminated commissions and retail participation has surged. The terminology in this FAQ is not academic — it is the language of every trade ticket, every risk screen, and every strategy discussion.
Getting the definitions right matters because options are leveraged instruments that magnify gains and losses alike. A misunderstanding of assignment, exercise, or the Greeks does not just cost knowledge — it costs capital. The traders who consistently profit are the ones who internalize these terms so deeply that evaluating a trade becomes second nature rather than a lookup exercise.
If you want to move beyond definitions and start tracking unusual flow, analyzing gamma exposure, and scanning for setups, OptionScout offers options flow analysis, a GEX view, a scanner, alerts, portfolio tracking, and an advisor. Pair that with a solid grasp of the options Greeks and you have a foundation worth building on.
FAQ
What is a put and call option contract?
A call option contract gives the buyer the right to purchase shares at a predetermined strike price before the contract expires. A put option contract gives the buyer the right to sell shares at the strike price before expiration. In both cases, the seller accepts the obligation to fulfill the contract if the buyer exercises. Neither the call buyer nor the put buyer is obligated to act — they pay a premium for the right, not the requirement.
Which is better, a put or a call option?
Neither is inherently superior. Calls are the right tool when you expect the underlying to rise, while puts work when you expect it to fall or when you want to hedge a long stock position. Many strategies combine both: a straddle uses a call and a put at the same strike to profit from volatility regardless of direction. The better choice always depends on your specific market thesis and risk tolerance.
Is it risky to buy a put option?
The maximum loss from buying a put is limited to the premium you paid, which makes it structurally less risky than shorting stock outright. However, the option can expire worthless if the underlying does not fall below the strike price, meaning you lose the full premium. The real risk lies in position sizing and timing — a string of small losses on expired puts adds up quickly if you are not disciplined.
What is the difference between intrinsic value and extrinsic value?
Intrinsic value is the amount an option is currently in the money. For a put, it equals the strike price minus the stock price when that difference is positive. Extrinsic value is the remaining premium above intrinsic value, reflecting the time left until expiration and the level of implied volatility. As expiration approaches, extrinsic value decays toward zero — a force that benefits sellers and erodes the positions of buyers.
What does assignment mean in options trading?
Assignment occurs when the seller of an option is obligated to fulfill the terms of the contract. If you sold a call and it is assigned, you must sell shares at the strike price. If you sold a put and it is assigned, you must buy shares at the strike price. Assignment can happen at any time for American-style options and is most common when the option is deep in the money near expiration.
Sources
[1] schwab.com, "Basic Call and Put Options Strategies | Charles Schwab". https://www.schwab.com/learn/story/basic-call-and-put-options-strategies
[2] macrohive.com, "Volatility: Definition and Meaning in Global Markets", 2023-03-24T09:15:59+00:00. https://macrohive.com/hive-explainers/explainer-what-is-implied-volatility/
