An option is a contract that gives you the right – but not the obligation – to buy or sell a share at a fixed price before a set date. You pay a small fee, the premium, for that right. A call is the right to buy; a put is the right to sell.

You are not buying the company, the way you do with a stock – you are buying a right to act on its share price. This guide explains exactly how that works, in plain English, with worked numbers throughout.

A stock is ownership. An option is a contract

The quickest way to grasp an option is by contrast with a stock. When you buy a stock, you become a part-owner of a company, with a claim on its assets and earnings and no expiry date on your holding. When you buy an option, you own something fundamentally different: a contract with a fixed lifespan that gives you a right tied to the stock’s price.

People use options for three broad reasons: to speculate on a price move using far less capital than buying the shares outright, to hedge an existing holding against a fall, and to generate income by selling options to others. The rest of this guide builds up the pieces you need to understand all three.

Call options – the right to buy

A call option gives you the right to buy a share at a fixed price (the strike price) before the expiry date. You buy a call when you expect the price to rise.

Your maximum loss is the premium – $300, and no more, however far the stock falls. Above the $53 breakeven your profit rises with the share price, in principle without limit. That asymmetry – capped loss, open-ended gain – is the defining feature of buying a call.

Put options – the right to sell

A put option is the mirror image: it gives you the right to sell a share at the strike price before expiry. You buy a put when you expect the price to fall, or to protect a holding you already own – much like buying insurance.

As with a call, the buyer’s loss is limited to the premium paid. The profit grows as the stock falls below the breakeven (strike minus premium).

The premium – intrinsic value and time value

Every premium is made of two parts – intrinsic value and time value – and they behave very differently as time passes and the stock moves.

• Intrinsic value is the profit you could lock in by exercising right now. For a call it is the stock price minus the strike (never below zero); for a put it is the strike minus the stock price.
• Time value is everything above intrinsic value – what the market charges for the possibility of future movement. It is driven by time to expiry, implied volatility and interest rates, and it always decays toward zero as expiry approaches.

At expiry, time value is gone and only intrinsic value remains. An out-of-the-money option at expiry is worth exactly nothing.

In the money, at the money, out of the money

These three terms – “moneyness” – describe the relationship between the current stock price and the strike, and they drive an option’s premium, risk and probability of paying off.

At-the-money options carry the most time value and tend to dominate trading volume, because they are the most sensitive to a move in the underlying.

Expiration – the ticking clock

Every option has an expiry date, after which an unexercised contract is worthless. That deadline makes time one of the most powerful forces in options pricing.

• Weekly options expire each Friday – cheap, but you need to be right quickly, and time decay is fierce in the final days.
• Monthly options expire on the third Friday of the month – the most liquid, and a balanced choice for most strategies (typically 30 to 60 days out).
• LEAPS are long-dated options expiring one to three years out – far higher premium, far slower decay, used for longer-term positions.

American vs European style – when can you act?

Every option is either American-style or European-style, and the difference is simply when you may exercise.

American style is more flexible for buyers but carries early-assignment risk for sellers; European style has simpler pricing and no early assignment.

Buyers vs sellers – the asymmetry of risk

Every trade has two sides, and they carry very different risk. This is why most beginners start as buyers.

A buyer’s risk is defined and known upfront. A seller’s risk is open-ended – especially when writing calls without owning the stock – which is why selling options is an advanced activity.

Closing a position – sell before expiry

Most retail traders never actually exercise their options. Instead they sell the option itself before expiry to realise a gain or cut a loss. Selling captures both intrinsic and any remaining time value, needs no share transaction, and is usually simpler for tax. Exercising early is usually suboptimal because it throws away the remaining time value, and letting an option expire only makes sense when it is out of the money and worth nothing.

A full trade, start to finish

Here is how every piece fits together in one complete trade.

That is a +90% return on the $200 at risk. Buying 100 shares outright for $5,000 and selling at $56 would have made $600 – a larger cash profit, but only a +12% return on far more capital. Same view, very different leverage. Leverage cuts both ways: had the stock not risen, the entire $200 premium could have been lost.