The difference between Trade and an Investment is a trade is short or shorter then six months. An investment is long term or lasts more then six months. In trade you look for a catalyst, which will tell if the stock needs to be sold or kept. An investment can pay a dividend, which is a portion of money the company has left over after their overhead is paid that they give to stock holders. When a stock decreases in an investment, you can either sell the stock, or buy more of the same stock lowering you the price per stock. When a stock decreases in a trade, you can wait for your catalyst to happen and if already has then you can sell the stock. Short sell is when you borrow stocks from a company and you sale the stocks for your own gain. Then you replace the stocks you borrowed but keep the gain.