Selling the call obligates you to sell stock you already own at strike price if the option is assigned. One can run this strategy after they have already seen nice gains on the stock. Often, they will sell calls, so if the stock price goes up, they are willing to part with the stock and take the profit....
Covered calls can also be used to achieve income on the stock above and beyond any dividends. The goal in that case is for the options to expire worthless.
If you buy the stock and sell the calls all at the same time, it’s called a ”Buy / Write.” Some investors use a Buy / Write as a way to lower the cost basis of a stock they have just purchased.
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