Regulation D provides exemptions from the registration requirements of the Securities Act of 1933 for certain offerings of securities. This allows companies to raise capital without the lengthy process of registration, making it attractive for startups and private companies. Regulation D consists of three main rules: Rule 504, Rule 505, and Rule 506, each with specific requirements and limitations. Rule 506 is often used for raising capital, allowing an unlimited amount of money to be raised from accredited investors and up to 35 non-accredited investors, while Rule 504 permits offerings up to $5 million within a 12-month period.