Public companies are businesses that have sold shares to the public through a stock exchange, allowing anyone to buy ownership in the company. These shares are traded on platforms like the New York Stock Exchange or the NASDAQ, making it easier for the company to raise capital for growth and operations. Being public means that these companies must follow strict regulations and disclose financial information regularly to ensure transparency for their investors. This includes quarterly earnings reports and annual filings, which help shareholders make informed decisions about their investments in the company.