For many, trading is simply the buying and selling of goods under a certain period given by the market. It can also be connoted that a person does trading for the sake of reselling or sharing. Basically, the idea presented is correct. To be more concise, that idea is the basis of all trading systems or primarily the stock market.
In the stock market, you can purchase and sell any variety of products as long as you know that there will be people who will be interested to buy the product. You must also think about the money you have and the amount of the commodity that you intend to buy.
