The smartphone era has evolved quickly. Just a few years ago, consumer-facing brands saw mobile apps as a curiosity: some embraced the trend and rolled one out, while others decided not to bother. It wasn’t seen as a big deal either way. In 2018, though, the landscape is a little different. Every company must have an app if it wants to stay competitive. The New York Times emphatically underscored this point, calling attention to Forrester Analytics data showing that U.S. shoppers are expected to make $118 billion in retail purchases using their smartphones in 2018.

Mobile apps have value for both brands and their customers. A survey from digital development company WillowTree found that people appreciate having access to sales, limited-edition products, and events, as well as being able to earn loyalty points and rewards by using apps. Companies, likewise, said they see value in developing apps because they can track customers’ interests, customize ads, and tailor-make discounts and promotions that will keep people coming back.

“If you’re a brand and you don’t have an app strategy or you aren’t investing in your app development, then it’s going to be really hard for you to engage and monetize the fastest growing population, which are mobile shoppers,” said Jon Hudson, VP of customer solutions and innovation at digital marketing firm Criteo.

There are plenty of success stories about branded mobile apps. Panera Bread’s app has become a big hit, as it allows people to quickly place orders and win rewards. Regal Cinemas uses a mobile platform that lets people buy movie tickets easily through Fandango. Walgreens has a mobile app that makes life easier for pharmacy patrons, using features such as daily pill reminders.

There’s a drawback, though. If your app isn’t a high-quality product, you risk losing people. WillowTree found that almost half of people find the majority of the apps they download to be unhelpful, and 22 percent of people say they’ve deleted more than half of their brand apps. A bad app experience can mean fewer customers.

One such customer, Jared Guynes, told the Times that he became disillusioned with Chili’s Grill and Bar when an annoying app sent him “a flurry of push notifications” immediately after he began using it.

“I thought, chill out, Chili’s,” Guynes said. “Let me get home and digest the food.”