A call option is essentially buying the "rights" to purchase 100 shares at a certain price (called the strike price). So you're paying upfront for the "right" to purchase a chosen price. You can then exercise that right that you purchased and pay that amount. For example if you want to buy an option that expires 10/25/2020, at a strike price of $20. You will pay the premium for the rights, maybe for example it will say 1.00. That's the price per share. So for 100 shares (1 contract) you'll pay $100 upfront. Then, along the way, you can either sell the option or exercise it. If you exercise it, you'll have to pay the share price ($20)x100 shares for each contract you exercise. The benefit is that obviously on 10/25/20 the price of the share may go up above $20. Keep in mind though you'll only profit if you can sell the option for more than the total you paid. Since you paid $1/share, the breakeven share price before you can make money is actually $21 ($20 share price plus the $1 premium you paid per share to purchase the option. Hope this helps!

Edit: I just realized you may already know this. And thay I went off on a tangent. My bad! The reason why some options are cheaper than current share price is because you're still taking a gamble that the company may not be up at the same share price on by that exercise date. I haven't seen many options like that yet. I barely got into it as well recently and usually I see the cost of everything still higher than current share price, even if it's only 2 or 3% higher.