Amazon.com (AMZN -1.43%) reported some stellar results in Q1, capturing how e-commerce continues to boom even as the COVID-19 pandemic begins to subside and many people are returning to work and spending more time outside of their homes.

Here's a closer look at Amazon's strong first-quarter results and why they signal that these are likely still early days for e-commerce.

Boxes in an Amazon fulfillment center

Amazon fulfillment center. Image source: Amazon.com.

Surging sales

Amazon's first-quarter sales soared 44% year over year to $108.5 billion, smashing analysts' average estimate for revenue of $104.5 billion during the period. 

Impressively, Amazon's 44% year-over-year growth rate was equal to its growth rate in Q4. Analysts were modeling for a deceleration during Q1 -- and rightly so; not only was Amazon up against a tougher comparison in Q1 (26% revenue growth in the year-ago quarter) than it was in Q4 (21% growth in the fourth quarter of 2019) but Amazon's fourth-quarter of 2020 benefited from a Prime Day that was rescheduled from its typical summer timeframe to October. With this backdrop in mind, Amazon's ability to maintain its 44% growth rate in Q1 is particularly notable.

International momentum

But even Amazon's 44% growth rate for its total sales arguably understates the company's momentum. Consider that Amazon's international segment, which excludes international sales from its cloud-computing business, saw revenue grow 50% year over year on a currency-neutral basis, in line with its international growth rate in the fourth quarter of 2020.

In Amazon's first-quarter earnings call, CFO Brian Olsavsky noted that its international e-commerce sales are growing at triple the rate they were before COVID-19. He suggests that there's been a significant advancement in the adoption of e-commerce internationally.

Strong guidance

Also putting the spotlight on Amazon's momentum is the company's rosy outlook for Q2. Management guided for sales for the quarter to be between $110 billion and $116 billion, representing 24% to 30% year-over-year growth. While this implies a deceleration from Amazon's 44% revenue growth in Q1, it's very impressive growth considering the comparison Amazon is up against; second-quarter 2020 revenue was up 40% year over year -- a huge acceleration from the 26% growth the company saw in the first quarter of 2020.

Also highlighting Amazon's momentum, even the low end of its second-quarter revenue guidance range is up sequentially from Amazon's $108.5 billion of first-quarter revenue. Management doesn't always guide for such a meaningful sequential increase in Q2. For instance, consider how Amazon guided for second-quarter 2019 revenue to be between $59.5 billion and $63.5 billion after reporting first-quarter revenue of $59.7 billion. Clearly, Amazon management has great confidence in its sales momentum.

While investors should naturally expect a deceleration in Amazon's growth rate in the coming quarters as the e-commerce giant laps tough comparisons, it's clear that there are still some major tailwinds working in Amazon's favor.