Every portfolio should have some "forever" stocks -- companies so good that they're worth holding for a very, very long time.

They're like keepsakes -- oftentimes passed down from parent to child. They can be the bedrock of true generational wealth. So, what types of stocks fit that bill? Well, let's have a look at three that I consider forever stocks.

Jar full of $100 bills.

Image source: Getty Images.

Amazon

Tech giant Amazon (AMZN 2.94%) is a mainstay of my investment portfolio and will remain so for many years to come, for three key reasons.

  1. Relentless focus on the customer: This was the creed of founder and former CEO Jeff Bezos, and it still permeates the company today. Look no further than the company's mission statement: "Amazon's mission is to be Earth's most customer-centric company."
  2. Innovation: Amazon has developed numerous innovations, ranging from its sprawling fulfillment network to its vast array of data centers that make it the global leader in cloud computing services.
  3. Delivering shareholder value: The company constantly reevaluates its finances and workforce, with a focus on balancing shareholder returns and reinvestment in the business. Over the last 10 years, Amazon shares have returned 659%, meaning a $10,000 investment in early 2014 would be worth nearly $76,000 as of this writing.

AMZN Total Return Level Chart

AMZN Total Return Level data by YCharts.

In short, Amazon is a great company. What's more, with analysts expecting it to grow sales by 11% this year as its long-term investments in regional distribution combine with a rebound in enterprise cloud spending.

Coca-Cola

Next up is Coca-Cola (KO -0.62%), the legendary maker of iconic beverage brands such as Coke, Sprite, Powerade, Fanta, Schweppes, and Minute Maid, among many others.

The reason I intend to own Coca-Cola stock forever is that the company delivers consistent earnings growth. Over the last five years, Coca-Cola has grown its net income from $6.7 billion to $10.8 billion. Quarterly earnings per share (EPS) have increased at an average rate of 19%. Moreover, free cash flow -- the lifeblood of a mature, dividend-paying company -- has grown from $6.0 billion to more than $10.2 billion.

That, in turn, has allowed Coca-Cola to increase its dividend consistently. In fact, the company has raised its dividend each year, dating back 62 years -- representing one of the longest such streaks on Wall Street.

And what a dividend it is! The company pays $1.84 per share -- good for a dividend yield of 3.1% at the current share price. That's more than twice the 1.4% average yield of the S&P 500 index.

To see how important those dividend payments are over the long term, consider this chart which shows the growth of a $10,000 investment in Coca-Cola over the last 30 years.

KO Chart

KO data by YCharts.

The company's steadily growing payouts make an enormous difference, boosting the total return of the investment from $56,000 to more than $116,000 (with dividend reinvestment).

In short, Coca-Cola remains a solid stock that investors can rely on for the very long-term -- a nearly perfect forever stock.

Nvidia

Finally, there's Nvidia (NVDA -1.81%). The reason to own Nvidia forever is simple: Technology is the future.

Never has this been more obvious than right now. Whether it's artificial intelligence (AI), autonomous driving, advanced robotics, or gene editing, it's clear that the next wave of technological breakthroughs will have one thing in common: They will require tremendous amounts of computing power.

That means demand for advanced semiconductors -- the type used in the supercomputers and server farms of today and tomorrow -- will continue to grow massively in the years to come.

Nvidia, which many experts believe makes the best and fastest chips for high-performance computing, stands to benefit enormously from the rise of AI and other cutting-edge tech innovations.

That's why Wall Street analysts are raising their forecasts for its future sales at a breakneck pace. The consensus among analysts is that Nvidia will report over $92 billion in revenue for its fiscal 2025. Over the last 12 months, it reported $45 billion in revenues.

Nevertheless, Nvidia isn't a perfect forever stock for everyone. Income-seeking investors will be better off looking elsewhere, as will value-oriented investors and those who lack the stomach for stocks with high volatility.

However, for long-term investors who a ready to hold on through the inevitable volatility, Nvidia is a forever stock with a high ceiling, and one worth seriously considering.