One of this year's biggest gainers is Twilio Inc. (NYSE:TWLO). The leading provider of in-app communications solutions has seen its stock more than triple -- up a whopping 242% -- in 2018. It hit fresh all-time highs late last month.

A stock doesn't just transform itself into a game-changing wealth creator. Twilio has earned this year's upticks. Let's take a closer look at why Twilio investors are smiling this year. 

A Twilio presentation at its 2016 Signal developer conference.

Image source: Twilio.

1. Accelerating growth is a good look

There are few things as tantalizing to a growth stock investor as when a company is cranking out accelerating top-line growth. Even the best growth stocks slow over time, but when a company is putting the pedal to the metal, it's something special. 

Twilio's revenue growth went from a hearty 40.6% top-line surge in the fourth quarter of last year, to a 47.8% year-over-year leap in the first quarter, and then 54.1% in its latest financial report. This is the kind of uptick in growth that defies gravity as it redefines future growth expectations. It's not a surprise that many of this year's biggest winners have all been coming through with accelerating revenue growth.  

2. Last year's fears were overblown

Starting lines matter, and in Twilio's case, it probably helped that the shares fell 18% in 2017. The stock came under pressure early last year when it warned that Uber -- at the time one of its two largest clients -- was checking out Twilio rivals and in-house solutions to satisfy some of its in-app communication needs. It didn't help when Lyft followed suit. 

Potentially losing a big account stings, and it naturally sends a problematic message to other developers leaning on Twilio's cloud-based platform. The pessimism didn't stick around. Orders continued to pick up elsewhere, and more developers signed up with Twilio. By the end of the year, Uber was accounting for just 5% of Twilio's business and was no longer the needle-mover it was a couple of years earlier. 

3. Exceeding expectations naturally helps

Total and base revenue rose 54% in Twilio's blowout second quarter, well ahead of the 35% to 37% gain it was forecasting three months earlier. It's not just the top line that surpassed internal and Wall Street targets. The $0.03 per share adjusted profit that Twilio posted in its latest financial report also bucked the company's earlier guidance and analyst models calling for more red ink.

We're still early in Twilio's growth cycle, so don't expect the bottom line to move the stock at this point. Investors will continue to view revenue growth as the best sign of the platform's popularity and the stock's worth. 

Twilio keeps boosting its projections, and it's not the only one. This holiday-shortened trading week is kicking off on Tuesday with KeyBanc analyst Brent Bracelin upgrading the stock. Armed with a $99 price target, he feels that revenue could approach $2 billion for Twilio by 2022 -- a fivefold increase from the $399 million it delivered last year. Twilio is clearly one of this year's hottest stocks, and it's not showing any signs of slowing down.