Covered call
Selling one call option against each 100 shares already owned. The premium is collected up front, and gains above the strike are capped.
In a covered call, the shares cover the obligation of the short call. If the call is assigned, which can happen before expiration, the shares are delivered at the strike.
The premium received lowers the effective cost of the shares, and in exchange the position gives up any rise in the stock above the strike for the life of the call. The shares still carry their full downside, reduced only by the premium collected. Covered calls are often written out of the money so there is room for the stock to rise before the strike is reached.
Illustrative example (hypothetical numbers, not a real trade): an investor owns 100 shares at $50 and sells one $55 call for $1.50, receiving $150. If the stock is at $60 at expiration, the shares are called away at $55, and the position is worth $5,500 plus the $150 received. If the stock is at $45, the shares are worth $4,500 and the $150 offsets part of the decline.