Stocks
Let's confine ourselves to equities and the equity markets. Investment professionals often use the word stocks as synonymous with companies—publicly-traded companies, of course. They might refer to energy stocks, value stocks, large- or small-cap stocks, food-sector stocks, blue-chip stocks, and so on. In each case, these categories don't refer so much to the stocks themselves as to the corporations that issued them.

Financial pros also refer to common stock and preferred stock, but, actually, these aren't types of stock but types of shares.

So, when people talk about the stock of a company, they are most often talking about their common stock. Common stock represents shares of ownership in a corporation and the type of stock in which most people invest. When people talk about stocks they are usually referring to common stock. In fact, the great majority of stock is issued is in this form. Common shares represent a claim on profits (dividends) and confer voting rights. Investors most often get one vote per share-owned to elect board members who oversee the major decisions made by management. Stockholders thus have the ability to exercise control over corporate policy and management issues compared to preferred shareholders.