Understanding Options: A Plain-English Starting Point
Calls, puts, strike prices and premiums — the essential vocabulary and mechanics behind options contracts, explained without the jargon.
Tom Hartley
Personal Finance Editor
An option is a contract that gives its holder the right, but not the obligation, to buy or sell a specific stock at a predetermined price — known as the strike price — before a set expiry date. That single distinction, right without obligation, is what separates options from simply owning shares outright.
There are two basic types. A call option gives the holder the right to buy the underlying stock at the strike price, and tends to gain value as the stock rises. A put option gives the right to sell at the strike price, and tends to gain value as the stock falls. Buying either type costs a premium, paid upfront, which is the maximum a buyer can lose if the trade doesn't work out.
Selling — or 'writing' — options works differently. A seller collects the premium upfront but takes on an obligation: if the buyer exercises their right, the seller must fulfil the other side of the trade. This is why selling uncovered options carries risk that can, in some cases, be larger than the premium collected.
Three factors dominate an option's price: how far the stock is from the strike (intrinsic value), how much time remains until expiry, and how volatile the market expects the stock to be. All else equal, more time and more expected volatility both make an option more expensive, because they widen the range of outcomes before expiry.
A common beginner mistake is treating options purely as a leveraged bet on direction, without accounting for time decay — the fact that an option loses value simply as expiry approaches, even if the stock doesn't move. This is why many new traders find that being right about direction isn't enough; timing and volatility matter just as much.
For most new investors, the more approachable starting point is a covered call — selling a call option against shares you already own — since the risk is capped by the stock you hold, rather than open-ended. Even so, options carry real risk of loss and are worth practising conceptually, on paper, before committing capital.