1. Rental Properties: Investing in real estate and renting out properties can provide a steady stream of passive income. By purchasing residential or commercial properties, you can earn rental income that covers your mortgage, expenses, and generates profit. This can be a long-term investment strategy with potential tax benefits. (Reference: Investopedia - Rental Property as a Passive Investment)

2. Dividend Stocks: Investing in dividend-paying stocks allows you to earn passive income through regular dividend payments. Companies that distribute profits to shareholders in the form of dividends can provide a reliable income stream, especially if you choose stable and well-established companies. (Reference: The Balance - Dividend Investing)

3. Peer-to-Peer Lending: Platforms like LendingClub or Prosper enable individuals to lend money directly to others, earning interest on the loans. By diversifying your loans across multiple borrowers, you can mitigate risk and earn passive income from the interest payments. (Reference: Investopedia - Peer-to-Peer Lending)

4. High-Yield Savings Accounts: While the interest rates may not be as high as other investment options, having a high-yield savings account can still generate passive income. These accounts offer a higher interest rate than traditional savings accounts, allowing your money to grow over time. (Reference: NerdWallet - Best High-Yield Savings Accounts)

5. Royalties: If you possess intellectual property such as books, music, or patents, you can earn passive income through royalties. Licensing your creations to others or receiving royalties from sales can provide a consistent income stream. (Reference: Entrepreneur - How to Earn Royalties)

6. Affiliate Marketing: By promoting products or services through your website, blog, or social media platforms, you can earn passive income through affiliate marketing. When someone makes a purchase using your unique affiliate link, you receive a commission. It is crucial to build a strong online presence and choose affiliate programs that align with your audience's interests. (Reference: Neil Patel - Affiliate Marketing Made Simple)

7. Online Courses or eBooks: Creating and selling online courses or eBooks can be a lucrative source of passive income. Once you develop the content, you can sell it repeatedly without much additional effort. Platforms like Udemy or Amazon Kindle Direct Publishing offer opportunities to reach a wide audience. (Reference: Forbes - How to Create and Sell an Online Course)

Remember, passive income requires initial effort, time, and investment. It's essential to conduct thorough research, seek professional advice, and diversify your income sources to maximize potential returns.