In short, it's anxiety that people experience when they think they might be missing out on a sweet deal. Customers weigh up the prospect of buying something now vs resisting the urge and coming to regret their restraint later.

Carefully tipping the scales in your favor by playing on that uncertainty in the mind of your visitor can be the difference between a sale made and a sale lost.

Studies have demonstrated that it is an efficient marketing technique for millennials (those born between 1981 and 1996). Here are the key numbers you need to know about their behavior:

1. 64% have experienced Fear of Missing Out (Strategy Online)
   
2. 60% said they made a compulsive purchase after experiencing FOMO, most likely within 24 hours (Strategy Online)
   
3. 33% have incited FOMO in their friends (Strategy Online)
   
4. Social media is the main FOMO driver: 45% can't go 12 hours without checking their accounts (Strategy Online). Facebook is the top contributor at 72%
   
5. 40% spent money they didn't have and gone into debt to keep up with peers (CNBC)
6. 69% buy clothes for reasons beyond basic necessity (Forbes)

A classic trick to adopt. Make some of your products available only for a certain period of time - and notify your customers that once the offer's up, it's up for good. Come good on that promise too, otherwise shoppers will stop believing you.

The two standout examples of this tac are Starbucks and The 5th. Starbucks serves an iced pumpkin latte - but only during the holiday season, roughly from early September to early November. That limited lifespan makes the drink all the more desirable.

The 5th, meanwhile, is an Australian-based watch-maker, but with a twist… You can only order watches from their new collection on the 5th of each month - and there are only 250 pieces available. The craving for a new timepiece from the company's cult-like following is immense, as you can guess. By the way, The 5th combines a limited time offer with another FOMO trick - quantity scarcity.

Scarcity can apply to time (limited-time offers) and also to quantity. In the case of The 5th, it's both: 250 new pieces available on the 5th of each month. But there are other notable examples.

Tell me, do you think a book can be worth $400? The expert marketer Seth Godin certainly believes it can. 6 years ago he released a book and charged exactly $400. He also wrote a blog post to convince the fence-sitters of the book's worth.

The devil is in the details here: 1) Seth Godin is a renowned expert, 2) he wrote a massive book (800 pages long) and 3) only 2,400 copies were released.

In the end, he sold all of them.

This means finding famous people to be ambassadors of your brand. Ever wondered why celebrities earn so much from advertising? The reason is simple: even well-established brands fork out huge money for Hollywood stars to promote their products.

Why does it work? People like celebs. They strive to be like them. If their idols are using something, then it must be good. That's exactly why Reebok and Adidas went with Cardi B and Kanye West respectively.

Cardi B's involvement saw Reebok get 3.5 million likes and over 15,000 comments on Instagram. Kanye West wearing Adidas' Yeezy shoes was a storming success too. Of course it doesn't have to be someone as famous for your brand, but you get the idea of how it works.

It's the CTA that ultimately gets you sales. So instead of using a simple "add-to-cart" or "buy", you can play around with it too. And one way of doing that is incorporating Fear of Missing Out as part of the package.

Words like "now" and "free" work well, however, only your imagination is the limit here. DesignCuts have come with their own version of a FOMO CTA: it's an unconventional approach of saying there's a massive discount for the service - but it does work because of the difference with the usual price.

This is achieved through exclusivity. Offer deals to your loyal customers that casual shoppers can't get. It can be anything from free shipping to early access to new products. People will jump onto that because they crave to be part of a special, exclusive, group.

Amazon exploits this psychological trait particularly well with their Prime subscription. They offer many perks: fast and free delivery, access to their Prime Video and Music streaming services and much more. $12-$15 feels like a small price to pay for all these goodies. 100M+ people have already taken the bait.

As a marketer you are taught the exact opposite. Your content should be re-usable, it should stick around to build authority, be populated with backlinks, attract traffic…

But expiring content works well too. It's why Snapchat is so hugely popular and successful: once it runs out of time, it's gone forever. Either you see it now, or you lose the chance. Teenagers can't get off their phones as a result.

What the numbers say:

• 9 out of 10 consumers quote free shipping as the main incentive for buying online;
  
• 93% are willing to take action to qualify for free shipping;
  
• orders with free shipping average 30% more;
  
• unexpected high fees at checkout, such as from shipping, is the main reason why people abandon their cart
  

So it only makes sense to leverage the craving for free shipping. Make it a limited-time offer though, and people will pummel that CTA button senseless. Alternatively, you can offer free shipping after visitors cross a certain order value threshold.

There are several ways you can go about applying this principle. The straightforward one would be displaying the overall rating at the top of your product page, with individual reviews from customers shown at the bottom. 89% of users check reviews before buying something. 79% add they trust online reviews as much as personal recommendations. Reviews from peers is certainly a powerful weapon. You can further instill FOMO with this tactic by adding how many users are buying/have bought the product recently - as Ahrefs does.

Another possible option is displaying social proof in the form of approval from industry experts. Gong does that particularly well when they promote their app through a Shopify Plus rep. Notice how even the quote incites FOMO.

Finally, you can equip your products with a "best seller" or "most popular" label - or even say something like "selling fast" or "only X left in stock" on the product page. This can serve as both a recommendation from other people and an incentive to act fast while there's still something available. Amazon (first picture) and Marks & Spencer (second picture) do that well.

One of the most powerful drivers behind your consumers' decision to make a purchase is if they are offered something free. Their fear of missing out on something they don't have to pay for will cause them to take up that offer. Last year Apple executed this to perfection by offering a free pair of mightily-popular Beats headphones if you bought their Mac or iPad Pro.

Before you consider leaning too heavily into FOMO techniques described above, remember one simple thing: FOMO brings out mostly negative emotions in people. We are not making stuff up: here's what a study from Citizen Relations, quoted by Strategy Online, established:

• 39% reported feeling envy;
  
• 30% said they felt jealous;
  
• 21% said they felt sad or disappointed;
  
• and only 29% reported feeling happiness.

There's even an anti-FOMO movement called JOMO (Joy of Missing Out). It's centered around the idea that you don't have to worry and be anxious most of the time that you are missing out on a product or an experience. Instead you can simply enjoy what you already have, or embrace the free time that's suddenly appeared when plans get canceled.

Finally, it'd be remiss of us not to mention that some savvy marketers flip FOMO upside-down purposefully by offering a digital detox experience. Most of the FOMO is created by peer pressure from social networks: Camp Grounded masterfully combat this addiction by inviting people to spend the weekend doing outdoor stuff. No digital devices are allowed.

There's no doubt FOMO is a powerful marketing tool which allows to increase sales if used sparingly and creatively. Some of the best brands all over the world, mammoths like Amazon, Apple and Adidas, effectively rely on it from time to time.

We hope that we've given you something to chew on above, things you can implement in your store to great effect. But remember not to overdo it: as is with many things in our lives, too much or too little won't bring about the desired results.