Apple (NASDAQ:AAPL) has become an iconic technology giant largely on the back of the success of the iPhone. That single product has provided more than 50% of its revenue in almost every quarter since 2012.

That's perhaps a cause for concerns for investors, simply because while the iPhone has been dominant, it's possible it could someday lose market share. Of course, a lot of companies have tried to unseat Apple and, so far, that has not happened.

Apple CEO Tim Cook

Apple's CEO Tim Cook explained how well the company is doing outside of iPhone. Image source: Apple.

How is Apple doing?

While a slip in iPhone sales could cause major waves for Apple, the company has been sailing along. CEO Tim Cook laid out its astounding results in the company's recent first-quarter earnings call.

"We're thrilled to report Apple's biggest quarter ever, which set new all-time records in both revenue and earnings," he said. "We generated revenue of $91.8 billion, which is above the high end of our guidance range, with revenue growth accelerating for the third consecutive quarter."

The company also reported record revenue in the Americas, Europe, and the rest of Asia Pacific. Greater China also returned to growth, according to Cook. The CEO noted that the iPhone led the way, but he was careful to point out other strengths. 

"Our record performance was fueled by iPhone where December quarter revenue was up 8% year-over-year and by our fifth consecutive quarter of double-digit growth outside of iPhone, including a new all-time record for Services and another blowout quarter for Wearables," he said.

iPhone remains a revenue driver because Apple has created a market where many consumers upgrade their devices every year or two. That creates a situation that benefits Apple, because once consumers have the company's phone, they generally use its services.

"Turning to Services. Q1 revenue reached $12.7 billion, an all-time record growing 17% over last year," Cook said. "Once again, we saw double-digit growth in all five of our geographic segments and established new all-time records for multiple categories, including cloud services, music, payment services and our App Store search ad business, as well as setting a December quarter record for the App Store and Apple Care."

Basically, Apple's success in selling the iPhone puts people into its ecosystem. That then funnels them into various services and makes it more likely that they will buy iPads, Macs, and Apple Watches.

The iPhone may lead the way, but Cook pointed out that the company's Wearables category would be a Fortune 150 company on its own. The Mac division, he added, generated $7.2 billion and the iPad had $6 billion in revenue. All of these products feed off each other, the CEO explained.

"With our current lineup of iPad Pro, iPad Air, iPad mini and iPad, along with the new iPad OS, we give our customers an unparalleled tablet experience integrated -- integrating hardware, software, and services in a way that only Apple can," he said.

Is Apple a buy?

While the iPhone could weaken, it hasn't so far, and it has an incredibly loyal user base. Apple has built an impressive ecosystem around its phone that extends its relationship with its customers into a variety of areas outside its phone.

That's a recipe for success where each new service tightens Apple's hold on its customer base. Someone could, in theory, drop the iPhone, but that would mean walking away from Apple Music, Apple Pay, and other services.

This grip on its user base makes Apple a buy. The technology company can hold onto its customers and sell them new iPhones every year or two while adding new products and services to its mix. That will grow its revenue while making its users even more loyal -- a strong recipe for ongoing success.