A stock is also known as a share and represents the percentage ownership of a company. For example, if you own ten shares of a company with 100,000,000 total shares, you own 0.00001% of the company.
Stocks are not risk-free. Most people are familiar with low-risk savings accounts and Certificates of Deposit (CDs) that are, in many cases, insured by the Federal Deposit Insurance Corporation (FDIC).
Start buying stocks by picking a brokerage firm. In the past, an investor had to deal with a broker who placed a buy or sell order. Today, orders are placed directly by the investor online.