ReadWriteReflect offers a look back at major technology trends, products and companies of the past year.

This has been the year of the image—whether selfies, memes, pins or what-have-you. Social sites that emphasize pictures over text—Pinterest, Instagram and Tumblr being the chief examples—hit it big this year, both in user growth and in the billion-dollar valuations investors lined up to assign them.

Prior to 2013, many folks considered the Visual Web a fleeting trend that wouldn’t stick around. Here are some of the newsworthy moments that convinced the tech world otherwise.

Billion Dollar Buys

When Facebook bought Instagram for $1 billion in early 2012, not a few people thought the social network had lost its mind. Dumping that huge a sum on a photo-sharing network with next to no revenue struck some as wildly out of proportion.

Turns out that Facebook was just ahead of the curve, as billion dollar price tags have become the norm for Visual Web sites in 2013. This May, Yahoo! bought Tumblr for $1.1 billion. And from February to October, successive funding rounds took Pinterest’s valuation from $2.5 to $3.8 billion. 

For aging tech companies, an investment in the trendy new Visual Web was seen as a way to revitalize a business’s image—and its audience. 

Easy Mobile Access 

More than two thirds of visitors to We Heart It, a Visual Web free-for-all popular with teens, never visit the company’s desktop site. “Between text, images, and videos, images are the easiest to create and consume [on mobile devices],” said We Heart It CEO Ranah Edelin. “You can definitely scroll through 100 images faster than you can read 100 tweets.”

Most Visual Web sites have a mobile platform that is just as or more sophisticated than its desktop accessible one. Instagram is the most dramatic example. Since its desktop site is only a bare-bones version of its mobile app, nearly all of its traffic comes from phone use.

Pinterest built its iOS app on a new codebase before it even revamped the original code on the desktop site. More than 75 percent of Pinterest traffic happens on mobile, a spokesperson says.

A Hip, Young Audience

Where there are mobile-only users, there are bound to be young women. According to a Pew Internet and American Life survey—one of many similar studies—the largest demographic of mobile-only Internet browsers are young adults and women.

Log on to Pinterest, Instagram, Polyvore, or any of their competitors, and you’re bound to find evidence that young women and their interests are directing visual content. But this is no chicken and egg mystery—the Visual Web wasn’t specifically designed to appeal to young women.

Pinterest—founded by three men, by the way—didn’t become a shopping and design haven until early-adopter young women began populating it with their interests. Today, we perceive the Visual Web as young and feminine because young women were its first tastemakers.

This year, the Visual Web has been a go-to investment for aging tech companies hoping to appeal to the coveted teen and preteen demographic. That’s why Facebook snagged Instagram and why Yahoo! snagged Tumblr. If anyone is able to afford Pinterest, it’ll be a company looking to acquire a strong female demographic.

A Built In Revenue Plan

There’s a reason brands are flocking to the Visual Web in droves. There’s money to be made on the Visual Web in ways that are far less obtrusive to users than on other site formats. Facebook may be taking flack for its invasive new autoplay video ads, but Visual Web sites are faring much better. 

While Instagram users originally shunned ads in their image feeds, it appears they’ve ended up actually liking them. Instagram ads generate 32 times more “likes” than regular brand images, according to Curalate. A similar twist happened on Tumblr, where users originally freaked out about ads, but ending up treating them like any other GIFs.

Meanwhile, Pinterest spent the year experimenting on ways to make ads visible. Since a majority of pins feature products, the company had difficulty making actual promotions pop. While other sites are criticized as too intrusive, Pinterest ads struggle to stand out.  

That's to say nothing of the way visitors use the Visual Web as an online shopping destination. Wanelo doesn’t have ads and still generates money via affiliate links that deliver a cut of the revenue to the site when users click through and buy something.

We’ve had the technology to quickly load large quantities of images for a while. But what made 2013 the year that images finally surpassed text was nothing less than a perfect storm of convenience, hype, and revenue potential. 

We haven’t seen the end of the Visual Web. But its 2014 challenge will be for the major sites to stay relevant as more and more companies hop on the image-grid gravy train.

Lead image via Flickr user QThomas Bower, CC 2.0