Shares, or portions, represent ownership in a company. When individuals buy shares, they become shareholders, meaning they own a small part of that company. Companies issue shares to raise capital for growth and operations, and the value of these shares can fluctuate based on the company's performance and market conditions. Shareholders may receive dividends, which are payments made from the company's profits, and they can also benefit from selling their shares at a higher price than they paid. The stock market is where shares are bought and sold, allowing investors to trade portions of various companies like Apple or Tesla.