I heard about them at a seminar but couldn't quite get the idea through my head.

A covered call is a strategy in which an investor writes a call option contract while at the same time owning an equivalent number of shares of the underlying stock. Meaning if the option expires unexercised, the writer keeps the premium. If the holder exercises the option, the stock must be delivered, but, because the writer already owns the stock, risk is limited. This strategy is the most basic and most widely used strategy combining the flexibility of listed options with stock ownership.

A Covered Call is probably the most basic of Option Strategies, but it is also one of, if not, the safest strategies around.

Check out Options Education for a free course on covered calls and other options strategies. All trading has risks involved. It how you manage the risk that separates the newbies from the big boys.

You can also use them with ETF Funds!

Lots of pension and retirement funds actually use Covered Calls as part of their investing arsenal. It is a great way to add extra cash to your account against your long term holdings.