“Buy and hold” – this is a classic investment adage, and it makes sense.

Many great fortunes have been made by buying great stocks and holding on to them—for decades.

Those who have made over 1,000% or even 1,000% gains from stocks like Netflix (NASDAQ: NFLX ) or Amazon (NASDAQ: AMZN ) have done so by staying the course through the ups and downs over the years.

However, there is a useful distinction between buying and holding.

Because some company stocks are simply not suitable to be bought and held forever.

It may look like a good stock at first glance, but fortunes can change.

Many once-great companies have ended up consigned to the dustbin of history.

So buy with the intention of holding for the long term, but track your stocks regularly to make sure they're still on track and still looking promising.

Here are three solid companies worth knowing more about and considering buying into your portfolio.

1. Nike Nike (NYSE:NKE) is a sporting goods and apparel giant with a recent market capitalization of nearly $207 billion, making it a large-cap stock.

(That's much higher than Boeing's (NYSE: BA) market capitalization, but only about half that of Walmart (NYSE: WMT).) You may not realize it, but Nike includes not only the Nike brand, but also Converse and Jordan Brand.

As of fiscal 2020, the company had 338 retail stores in the United States and 758 retail stores outside the United States.

Nike's revenue in fiscal 2020 was $37.4 billion and net income was $2.5 billion, which means its net profit margin was 6.8%, well above the industry average.

Nike is a good long-term investment because it is always innovating—for example, launching lighter, more efficient running shoes and operating an efficient digital sales platform that already generates 30% of total revenue.

.

2. Microsoft Few people don’t know Microsoft (NASDAQ:MSFT).

In fact, it was recently ranked third on Interbrand's global brand value rankings, with its brand value estimated at $166 billion.

Coincidentally, Microsoft recently hired about 166,000 people worldwide, responsible for products such as Windows operating system, Office 365 office application suite, Xbox game system, Surface tablet computer, Azure cloud computing service, and even LinkedIn professional network.

(The company also owns Skype — a technology that’s being used more than ever during the current pandemic.) Microsoft is a huge company, with a market capitalization that recently approached $1.6 trillion, but it’s still trading in the double digits

The number grew at a rapid pace and demonstrated the ability to keep pace with the times, maintaining a pivotal position over the decades.

3. Pepsi-Cola Many people avoid companies with high technology content because they don’t know how these companies will survive decades later.

For example, in the video entertainment space, will another company emerge, perhaps offering a completely different technology that eclipses Netflix? Such questions do not bother investors in companies such as PepsiCo (NASDAQ:PEP), though.

Because consumers are likely to continue to demand a range of beverages and salty snacks over the coming decades.

PepsiCo's products are sold in more than 200 countries and regions, and it owns many familiar brands, such as Pepsi, Lay's, Mountain Dew, Doritos, Gatorade, Tropicana, Quaker Oats, Aquafina,

Cheetos, Tostitos and friitos, as well as SodaStream, Near East, Naked, Smartfood, Life and Sabra.

A full 22 of these brands generate more than $1 billion in annual sales.

Like the other companies mentioned above, PepsiCo has shown its ability to adapt to changing consumer tastes, such as responding to growing demand for energy drinks and healthier foods.

Its dividend has also been growing, with a recent yield of about 2.8%.

Nike, Microsoft and PepsiCo belong to completely different industries, but these three blue-chip giants all have some common characteristics, such as financial strength, strong brands and the ability to adapt to changing times.

Characteristics make them promising candidates for long-term buy-and-hold portfolios.

These companies also all offer a broad range of products, which is an advantage: If one or two businesses go awry, their losses can be recouped by outperforming parts of the business.

In short, these companies provide resilience.