Combinations are trades constructed with both a call and a put. There is a special type of combination known as a “synthetic.” The point of a synthetic is to create an options position that behaves like an underlying asset, but without actually controlling the asset. Why not just buy the stock? Maybe some legal or regulatory reason restricts you from owning it. But you may be allowed to create a synthetic position using options.
Just like many successful investors, options traders have a clear understanding of their financial goals and desired position in the market. The way you approach and think about money, in general, will have a direct impact on how you trade options. The best thing you can do before you fund your account and start trading is to clearly define your investing goals.
An option's price, its premium, tracks the price of its underlying futures contract which, in turn, tracks the price of the underlying cash. Therefore, the March T-bond option premium tracks the March T-bond futures price. The December S&P 500 index option follows the December S&P 500 index futures. The May soybean option tracks the May soybean futures contract. Because option prices track futures prices, speculators can use them to take advantage of price changes in the underlying commodity, and hedgers can protect their cash positions with them. Speculators can take outright positions in options. Options can also be used in hedging strategies with futures and cash positions.
As shown above, a long options trade has unlimited profit potential, and limited risk, but a short options trade has limited profit potential and unlimited risk. However, this is not a complete risk analysis, and in reality, short options trades have no more risk than individual stock trades (and actually have less risk than buy and hold stock trades).
The fee you are paying to buy the call option is called the premium (it's essentially the cost of buying the contract which will allow you to eventually buy the stock or security). In this sense, the premium of the call option is sort of like a down-payment like you would place on a house or car. When purchasing a call option, you agree with the seller on a strike price and are given the option to buy the security at a predetermined price (which doesn't change until the contract expires).