Options Basics
An option is a contract on the right to trade 100 shares at a fixed price before a deadline. Master five ideas first: rights vs obligations, strike, expiration, premium and break-even, and the split between intrinsic and extrinsic value.
Calls vs puts: rights and obligations
A call buyer pays premium for the right (not the obligation) to buy 100 shares at the strike. A put buyer pays for the right to sell 100 shares at the strike. The seller of either collects premium and takes on the matching obligation: a short call may be forced to deliver shares, a short put may be forced to buy them.
Strike price
The strike is the fixed price the contract references. It anchors moneyness: a call is in-the-money when spot is above the strike; a put is in-the-money when spot is below it. Strike choice trades probability against payoff, lower-probability strikes cost less but need a larger move.
Expiration
Expiration is the deadline for the thesis to play out. Time is an asset for the seller and a cost for the buyer: every day that passes, extrinsic value erodes (theta). Shorter-dated contracts move faster per dollar but leave little room for being early.
Premium and break-even
Premium is the per-share price paid or collected, multiplied by 100 per contract. For a long call, break-even at expiration is strike + premium; for a long put it is strike − premium. Break-even is a checkpoint, not a plan, you still need an exit, an invalidation level, and a catalyst window.
Intrinsic vs extrinsic value
Intrinsic value is the in-the-money amount that could be realized right now: max(spot − strike, 0) for a call. Extrinsic value is everything else, time, implied volatility, and demand. A directionally correct trade can still lose if extrinsic value collapses faster than intrinsic value builds.
Liquidity: volume, OI, spread
Volume is contracts traded today; open interest is contracts still outstanding; the bid/ask spread is the round-trip cost to enter and exit. Tight spreads with healthy volume and OI mean a theoretical edge is actually capturable. Illiquid strikes turn paper profits into trapped positions.
Assignment and exercise
Exercise is the long holder converting the contract into shares; assignment is a short holder being forced to fulfill the obligation. US equity options are American-style, so assignment can hit early, most often near expiration, around ex-dividend dates, and on deep in-the-money short calls.
Contract mechanics
One standard contract controls 100 shares, so a 2.50 premium quote costs 250 dollars. Multiplier, settlement style (shares vs cash), and adjustments after splits or special dividends all change what you actually own, read the contract specs before sizing.