Not too long ago, designing an appealing, functional, easy-to-use website was considered art. Or alchemy. It was a dark art.

The availability of do-it-yourself web design tools and fast, inexpensive web design services have made getting a good website less dark and less mysterious. But the evolution of web design has also made it less art and more science.

Today, web designers are more like engineers than artists. There’s no doubt that’s because web pages are no longer seen as simply online advertisements for your business. They are still that. But websites have become indisputable, non-negotiable business tools – not just engines of commerce but the engines of commerce for literally millions of businesses.

How, where and why people interact with websites is the essence of business survival. The science of how that happens – and making it happen through design – has become UX design. User experience design, for the uninitiated.

UX matters regardless if you’re Amazon.com or you’re about to launch your first website selling cupcakes. Your viewers, readers and customers can feel bad UX design, even if they don’t know exactly why they feel the way they do. That means it’s not a tech issue, it’s a public, customer issue.

Related: Can ‘User-Experience’ Experts Become ‘Customer-Experience’ Experts?

“We live in a time where everyone is in the technology business, regardless of what product or service you sell,” said Philip Tadros of Doejo. Doejo does full integrated marketing and management — they know what they’re talking about. “User Experience is everything. It’s rude to your customers and detrimental to your business if you choose to be lazy with design and engineering.”

If you’ve been to more than a dozen sites in your lifetime, you’ve probably felt bad UX — you just know it. For some people, bad UX design is what a typo is to me — a deal killer.

The shocking thing is that so many businesses, especially small ones and startups, have bad UX design but they don’t even know it. I’ve heard more than one bootstrapped entrepreneur put off UX or dismiss it outright as something they don’t need or can’t afford. For some reason, UX gets put on the “that would be nice to do” list instead of the “we’ve got to do that” list.

More business leaders would do better for themselves if they started to see UX and having a website as the same thing. As you wouldn’t have a car with no engine and no doors, it makes no sense to have a website with no UX engineering. Your customers won’t know to get in it or out of it and it won’t go anywhere.

Related: The Power of Persuasion: Using Brain Science to Get Users to Act

Moreover, when you consider the costs of other startup business requirements, decent UX planning is downright cheap. It’s possible you will spend more buying a good domain name than UX, which makes zero sense.

“Investing in a good domain name is important,” New York UX designer Elena Titova of Et 2 Graphics told me. “But having a good domain and no UX is like buying expensive real estate and not hiring a competent architect.”

Getting good UX help isn’t just good public relations and marketing advice, it’s good business advice. When you build a site, invest in UX design. Even if you already have a functioning website, bring in someone who can do a UX review – the only thing you have to gain is more customers.