Text is useful for conveying information, but it can easily fail to capture what we're feeling. And when you're using your digital devices to communicate with friends, family members, or significant others, feeling is often more important than facts. That's why people love using emoji. And it's why, on the Web, many often send GIFs, which are looping animated images that help explain the tone of your message.

On mobile, however, sending a GIF is a complicated ordeal. You have to open your phone's browser, go on Google, search images, hope a GIF comes up, save it to your device, and then send it via text. Basically, it sucks.

This is why David McIntosh, Erick Hachenburg, and Frank Nawabi created the GIF Keyboard. It's an iPhone app that let's you search for and easily send GIFs. Disappointed? Send a GIF of Patrick Stewart sinking his face into his palm. Excited? Jordan Peele thinks that's "nooice!" Just won an argument? Sign off with a GIF of a Kanye West mic drop.

There are countless apps you can use to find and send GIFs, but when the makers of GIF Keyboard launched their app, they set up its algorithms to help users find the GIF that best expressed their emotion.

The strategy worked. GIF Keyboard became so popular after its launch in September 2014 that a month later Apple featured it in a keynote. The startup, which was formerly known as Riffsy but recently changed its name to Tenor, is now an Apple partner as one of the GIF providers in the iPhone maker's new #images app.

Since forming in late 2013, Tenor has raised more than $14 million in funding and is now a team of 20. This little-known San Francisco startup makes the technology that powers the GIF search of practically any tool you use on the internet. If you've ever sent a GIF on #images, Facebook Messenger, Twitter, or Kik, you've used Tenor. The company has become such a dominant force in the world of GIFs that it is the sole partner Google turns to for GIF search help on the Gboard keyboard app.

"Take a simple example like 'Happy birthday.' On Facebook, we're always trying to figure out how to say 'Happy birthday' differently because 20 other people or 50 other people or 100 other people already said 'Happy birthday,'" says Hachenburg, explaining that GIFs help personalize a message.

Tenor claims more than 150 million monthly users, up 30 times since 2015. Those users access GIF Keyboard five times a day, and altogether they make more than 2 billion GIF searches every month--most based on finding the perfect GIF to express an emotion.

With the release of iOS 10 in mid September, Tenor's growth ought to continue skyrocketing. That's because iOS 10 more closely integrates apps like GIF Keyboard with Apple's iMessage. To accommodate iOS 10, Tenor drastically updated its app. Now, users can make GIFs of themselves or create GIF stickers that can be used to react to the things their friends send.

Sending a Tenor GIF is simple. On GIF Keyboard, or using any of the GIF buttons on the company's messaging partners, you search for the emotion, reaction, or expression you are trying to convey. Tap your choice and hit send.

As it keeps growing, Tenor is slowly turning its attention toward revenue. It may sound silly, but these three entrepreneurs have a plan to monetize GIFs. And it's all about emotion.

"What we're really doing as a business is indexing all this content around emotion," says McIntosh, who is the company's CEO. "Google's real asset is owning intent. Facebook's real asset is owning the social graph. We think about our asset as the emotional graph."

Think of the way ads on Google work. When you search for something, such as a used car, you have multiple car manufacturers bidding against each other to be the first link Google shows you at the top of your search results.

Tenor plans to introduce ads in a similar fashion. Instead of an ad based on a product or service you looked for, Tenor will give you an ad based on the emotion you want to express.

Want to send a good morning GIF? You might see GIFs from Starbucks or Dunkin' Donuts. Search for the term "love" and you could get sponsored GIFs from Tiffany & Co. or Pandora. Want to party? There's a chance you'll see GIF ads from Budweiser or Coors.

Tenor expects these potential advertisers to pay top bucks for two reasons. The first is the emotional aspect of the valuable data Tenor holds. The company has access to your thoughts and feelings, and if a brand can pay to associate itself with whatever you think of when you feel "happy," there are many marketers who will line up for that opportunity. This type of ad will not only show you GIFs from a brand when you search on GIF Keyboard, but it also has the potential to remind you of the feeling you searched for the next time you see that brand out in the real world.

Tenor's value also derives from messaging. People use Tenor when they send messages to one another. It's the space where you turn to your friends when you tell them about your plans, your frustrations, your jokes, your hopes, your wants, and your needs.

That is extremely hot real estate in mobile advertising. McIntosh estimates that on any given day, there are more than 200 billion mobile messages sent across the internet, and Tenor is well poised to tap into that market.

"Messaging is such a powerful communication because we talk about what we want to do, what we want to have, what we want to experience, and there are all these keywords," says Johnny Won, founder of Hyperstop, a tech consulting firm. Won often works with ad-tech companies.

Tenor is still a ways away from introducing ads. The earliest they would roll out ads would be sometime in 2017, Hachenburg says. Already, however, Tenor has worked with Hollywood studios to help them use GIFs as a way to promote their films, but they have yet to charge a dime for that type of service.

"We're two years in, we're still focused on product," says Hachenburg. "But we feel confident that these are things advertisers have always gravitated toward--creative, video, and data."

When the founders set off to start Tenor, they had no idea they would ultimately be creating an emotional graph. That came as a happy accident that resulted from their original intent: solving video on mobile.

Hachenburg had previously been CEO of Metacafe, a YouTube competitor, while Nawabi and McIntosh worked at Redux, a video discovery startup founded by McIntosh. They met in 2010, when Hachenburg and McIntosh both participated on a panel discussing the future of video. A few years later, they decided to team up. They had no firm ideas but knew they wanted to tackle the mobile video market.

They developed a video creation tool and found that people used it to make short clips to send to friends. This taught them an important lesson: On mobile, video was as much a medium for communication as it was for entertainment.

"No one had built a video company focused on communication and expression," McIntosh says.

With this in mind, McIntosh followed his instincts and hacked together an Android app that made it easy to send GIFs. Nawabi's friends caught wind of this and demanded to try it out. They installed it but were quickly disappointed. Android only sent links to GIFs, not actual GIFs. Worse, it was not possible on Android to quickly toggle between keyboards. If you used the GIF tool, you had to go back to settings and re-select another keyboard if you wanted to type again.

But what Android lacked in capabilities its chief rival would soon make up for. At the unveiling of iOS 8 in the summer of 2014, Apple announced that it would finally allow developers to create third-party keyboard apps. This was the opening the trio had been waiting for.

"It was almost as if [Apple was] looking at our user testing and were like 'Oh, we can fix that,'" Hachenburg says.

With iOS 8 coming, the team built GIF Keyboard and placed an emphasis on the app's search function. They knew that matching GIFs to a user's emotional intent was key. But after submitting the app, they experienced a slight delay. Apple initially rejected GIF Keyboard because it lacked a keyboard--forcing McIntosh to spend the next few hours hacking away and programming a keyboard for the app so it could be resubmitted.

"They saw this and were probably confused themselves like 'Whoa, what is this? You can't type anything!'" Nawabi says.

A few days later, the app was approved, and now, there is no higher ranked GIF-sharing app on mobile. Tenor's focus on emotion allowed it to build the best search tool for GIFs. That technology has evolved into a full blown emotional graph, and as Tenor matures and eyes revenue, tapping into our emotions will be key to growing a business.

"We have these 40 or 50 emotions throughout the day. We're expressing them on mobile," McIntosh says. "It feels like an opportunity that's hiding in plain sight."