As consumers' attention spans shrink, video ad lengths are, too. In social video content and on television, brands now have 15 seconds or less to tell their story. 

Fifteen seconds isn't much time. If you're lucky, you might be able to tie your shoes or crank out an email in that span. How can you possibly hope to share your brand's mission and values in such a short window?

Tough though it may be, brands can pack a lot of material into 15 seconds. Here's how to do it:

1. Show, don't tell

Fifteen seconds is too little for complex storytelling. For a brand like Coca-Cola, which stands for simple pleasures and "anywhere, anytime" refreshment, skipping verbal or written content altogether may be the best move. Notice how Sight Seven Productions' Coca-Cola commercial keeps it simple: A dripping bottle, a neutral background and a zoomed-in shot on the logo is all it takes.

Think about the emotions, rather than the words or phrases, people associate with your brand. If you're a resort brand, is a carefree couple walking along a beach enough to tell people what you stand for? As long as your logo makes an appearance, you may not need much else to get the message across.

2. Trust in text

Some brand stories take more explanation than others. If you need words to explain what your brand is all about, you may worry 15-second video ads won't work. But Monster's CMO revealed in a podcast hosted by B2B agency Renegade that he thinks most marketers are too quick to choose long-form content.

Consider how Monster's "Where Do Résumés Go?" ad does it. After a daughter asks her father where résumés go, the ad shows a messy pile of résumés. To connect the dots to Monster's brand, the ad shows a single sentence: "It's going to take more than a résumé to find you the right fit," followed by Monster's logo. That single screen of text is all it takes to position Monster as helpful, fit-focused and forward-thinking.

3. Skip the setup

Brand stories are not novels. Especially in short-form video ads, it isn't necessary to develop complex characters or build suspense. Travelocity's "Elephants" ad does neither, but it still manages to communicate the story of Travelocity: a fun, adventure-oriented online travel agency that sticks by its customers' side.

It doesn't matter to the viewer that the ad opens with no explanation of who the couple in the rowboat is, where they are or why elephants are crossing the lake. Travelocity's signature gnome standing on the boat's bow, the wild scene and the joke about elephants being "local traffic" provide plenty of context for Travelocity's story.

4. Vary the speed

Fitting more material in your video ad shouldn't be your only -- or even your primary -- reason for speeding it up. Use slow-motion and fast-forward editing techniques to emphasize key elements of your brand story.

Speedo makes swimwear that, as its name suggests, lets swimmers move quickly through the water. Notice how its Speedo Fit ad speeds up clips of athletes exercising underwater. Then, at key moments -- while showcasing Speedo gear or determined facial expressions -- the ad slows down. 

Speedo stands for speed, grit and athletic breakthroughs. If you're a fast-scaling software startup that helps people get more done, be sure your video content reflects that.

5. Get metaphorical

Your brand story doesn't have to be spelled out letter by letter for people to get it. Sometimes, less literal ads actually get the message across more effectively.

When 7-Eleven developed a television commercial for Doritos Loaded, it didn't show anything resembling a snack until halfway through the ad. What it did show were snapshots that say "bold and exciting": licking lips, matches igniting, martial arts maneuvers, firing neurons and more.

Your brand may have a long and storied history, but you don't need an essay to tell it. Get creative: A few seconds of carefully selected sounds, sights and text is all it takes to tell customers what you're all about.