What Is an Option? Why Options Exist and What They're Used For

An option is a contract that gives its buyer the right, but not the obligation, to buy or sell an asset at a fixed price -- the strike price -- until or at a set expiration date. A call is the right to buy; a put is the right to sell. The buyer pays a premium for that right, and the other side, the writer, receives the premium and takes on the obligation. This guide from OptionLab (option-graph.com) explains why options exist, how one works from start to finish, and what investors use them for.

Right vs. Obligation: The Two Sides of Every Option

An option always has two parties with very different positions. The buyer decides whether to use the right; the writer must perform if the buyer does. That asymmetry is the core idea behind every option, from the simplest call to a multi-leg strategy you might later build on option-graph.com.

Why Were Options Created?

The need behind options is old: people want to lock in a price today for a decision they will make later, and they will pay for that flexibility. In his Politics, Aristotle tells the story of the philosopher Thales, who paid small deposits during the winter for the use of olive presses and, when a large harvest came, rented them out at a high price. It is told as an anecdote about foresight, but it describes the logic of an option: a small payment now for the right to use something later on fixed terms.

For centuries such contracts were negotiated privately, which made it hard to find a counterparty and agree on terms. A turning point came on April 26, 1973, when the Chicago Board Options Exchange began trading standardized listed options -- contracts with set terms that anyone could buy or sell on an exchange. Standard terms are what make an option easy to price, compare and analyze, which is also why the same contract can be modeled on option-graph.com in a few clicks.

How an Option Works, From Purchase to Expiration

Every option goes through the same stages. Before expiration, its price moves with the underlying asset, with the time left and with volatility, and either side can usually close the position by trading it. At expiration, the result is fixed against the settlement price. The payoff charts on option-graph.com show that last stage: the result at expiration for each possible price.

A Worked Example: One Call and One Put

Premiums are quoted per share, and a standard US equity option contract covers 100 shares, so the cost of a contract is 100 times the quoted premium -- the same convention the calculator on option-graph.com uses by default. Suppose a stock trades at $100.

• Call: you buy one call with a $105 strike for $2.00 per share, so the contract costs $200. At expiration with the stock at $112, the call is worth $7 per share: $700 minus the $200 premium = +$500. At $107 you break even. At $104 the call expires worthless and the result is −$200, the premium.
• Put: you buy one put with a $95 strike for $1.50 per share, or $150 per contract. If the stock falls to $88, the put is worth $7 per share: $700 minus $150 = +$550. If the stock stays above $95, the put expires worthless and the loss is the $150 premium.

These are results at expiration. Before then, each option also carries time value, so its market price is usually above the simple payoff shown here. You can enter both trades on option-graph.com and read the breakeven and maximum loss for each.

What Options Are Used For

• Hedging: a put can limit the loss on shares you already own, at the cost of the premium.
• Defined-risk exposure: buying a call or a put sets the most you can lose in advance.
• Income for writers: a writer collects premiums, but takes on obligations whose losses can exceed them.
• A view on volatility: some combinations profit from a large move in either direction, or from a quiet market.

Each use has a cost. Protection is paid for with premium, and income from writing is paid for with risk. Comparing these trade-offs side by side on option-graph.com is often clearer than reasoning about them in the abstract.

Risks and Limitations

An option buyer can lose the entire premium, and this is a common outcome, not a rare one. A writer can lose much more than the premium received. Leverage magnifies percentage gains and losses alike, time value shrinks as expiration nears, and spreads and fees reduce every result. Options are complex instruments and are not suitable for every investor; understanding the exact position before trading matters more than any single example, so check its payoff on option-graph.com or with your broker's tools first. OptionLab (option-graph.com) is an educational and analytical tool and does not provide investment advice.

Summary

• An option is a right for the buyer and an obligation for the writer.
• A call is the right to buy, a put is the right to sell, both at the strike until expiration.
• Standardized exchange-listed contracts made options easier to trade and compare.
• At expiration only the payoff matters; before it, time value and volatility matter too.
• The buyer's loss is capped at the premium; the writer's is not.

To see these ideas on a chart, build a single call or put in the calculator on option-graph.com, then move on to the call and put guides.