Realty Income (O 0.62%) could be an excellent way to add income to your portfolio, especially while we're still in a high-rate environment. As I'm writing this, the real estate investment trust, or REIT, with more than 15,500 properties in its portfolio, has a 5.2% dividend yield, which it pays in monthly installments.

I've written several times that I believe Realty Income could be the best all-around dividend stock in the market. It has a great combination of long-term growth potential, steady income, and low volatility.

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An incredible dividend history

When it comes to income, the headline of this article doesn't even tell the full story. Realty Income went public on the NYSE in 1994 and has paid dividends every month since then, which is where the "30+ years" comes from. But the company was actually formed in 1969 (it just wasn't listed on a major exchange) and has been paying monthly since then. In all, Realty Income has made 672 consecutive monthly dividend payments. I'll save you the math. That's 56 years of dividends, every single month.

Realty Income not only has a stellar track record of paying dividends. It also increases them regularly. In fact, Realty Income has declared its 135th dividend increase since listing on the NYSE in 1994. The company has consistently grown its dividend at a rate of more than 4% annually, so not only will you get an excellent income stream, but one that should continue to grow faster than inflation over time.

Why Realty Income is a bulletproof dividend stock

As mentioned, Realty Income owns more than 15,500 properties (15,571 to be exact) in the U.S., U.K, and other European countries. It leases these properties to nearly 1,800 different tenants, mostly in the retail industry.

However, don't be worried about the cyclical nature of retail. Realty Income's tenants all fall into at least one of three categories:

• Non-discretionary: Retailers that sell things people need.
• Low-price: Retailers that sell discounted products. These tend to hold up well in tough economic conditions.
• Service-based: Businesses that sell services, not physical products. These aren't easily disrupted by e-commerce headwinds.

Not only that, but Realty Income's tenants sign triple-net leases that require the tenants to cover taxes, insurance, and most maintenance expenses. These leases are generally 10 or more years in length, with annual rent increases built in, allowing Realty Income to lock in a growing, predictable income stream for the long term. Plus, there's long-term upside potential as the underlying real estate assets increase in value.

The proof is in the performance. Not only is Realty Income a fantastic dividend stock, but it has produced a 13.6% annualized return since its 1994 NYSE debut. With dividends reinvested, a $10,000 investment back then would have grown to nearly $600,000 today.