Capitalization, or market capitalization, in stocks refers to the total market value of a company's outstanding shares. It's calculated by multiplying the current stock price by the total number of shares outstanding. For example, if a company has 10 million shares trading at $50 each, its market cap would be $500 million. Market cap helps investors categorize companies into different sizes—large-cap (over $10 billion), mid-cap ($2–$10 billion), and small-cap (under $2 billion). Larger-cap stocks are generally more stable but may offer slower growth, while smaller-cap stocks can be riskier but have higher growth potential.