A mobile app is the tip of an iceberg. It’s the thing that people see and interact with, but there’s a lot going on beneath the surface.

I’m an app developer. In fact, I spend almost as much time writing web services as I do writing the apps that consume them. Most people don’t understand what a web service is, so I just tell them I make apps. The back-end programming, servers, databases, and all the rest of it become minor details that make the app work, in spite of the fact that the servers are often where most of the complexity resides.

But an app is more than just client code and server code. An app is a marketing plan, a revenue model, customer support, fundraising, office management, HR, and a hundred other details. An app is a business.

Most people get it, but occasionally I run into someone who doesn’t. I’ve got an idea for an app, they’ll say. They’ll describe the features, the user interface, and the graphic design in great detail, and ask me how much it would cost to build. I’ll throw out a few questions about scalability or revenue and soon realize that they’re asking me to build the tip of an iceberg that doesn’t exist.

I suppose that a less scrupulous developer might take the money, build the app, and let it sink. I don’t like to see anyone fail, so I do my best to try to walk people through the whole lifecycle and point out the costs they may not see. Promotion is probably the biggest piece that people miss. The days when you could simply post an app to the app store and expect a lot of people to find it are long gone. Very few apps “go viral” or otherwise promote themselves. It’s a long, expensive slog to get anyone to notice you at all, let alone pay for your app.

In fact, selling an app is itself something of an outdated idea. These days most apps are free, the cost justified because they support a product or service sold outside of the app store. Apps that do charge frequently do so as in-app purchases or subscriptions instead of as a one-time price. All of this needs to considered when deciding how much to spend for app development.

I’ve had the good fortune to have worked at several software startups in the past decade. I was privy to millions of dollars raised and spent, not just on obvious things like salaries and advertising but on unexpected things like cloud servers and network bandwidth. The results were impressive, but to an outsider looking in, it is hard to picture the true costs. As an independent developer, I’m sometimes asked to do projects of equal or greater complexity by customers with a small fraction of the necessary budget.

Apps are inspiring. The phones in our pockets do almost magical things, and lots of people want to make the next great app. But no one has all the skills needed to do it alone. If you want to succeed, you’ve got to find the right combination of partners, investors, employees, and service providers. You’re not just creating an app, you’re building a business. It’s never easy, but nothing worth doing ever is.