What is an app? App is short for application, which is a software program. It can help people play games, read the news or find their way. You may use one every day, but how does it work? It may seem like magic, but it is not, so let's look inside it, one step at a time, and see how the small pieces fit. Take your time, and think about the ones you know.

Start with the phone itself, which you can hold in your hand and slip into a pocket when you are done. Hardware is the equipment, and software is the programs a computer runs. An app is one piece of it, and another kind runs the whole phone. It is called an operating system, and it is the main software that manages a computer's resources and lets other programs run. Android and iOS are two operating systems for phones.

Next, think about who makes these things, because somebody has to build each one before you can use it. Apps are made by developers, who may work alone or in a team. Computer programs are written in programming languages such as C, Python and C++. Here is a key point about how that works. A program is first written in a computer language by a person. Then it is translated into a form the computer can run. Keep that in mind as you read on.

Many of them are not alone, because they talk to machines that are far away. A server is a computer on a network that stores things like files and sends them to other devices. Here is how a chat goes. Network-connected apps often use HTTP to send and receive data. It sends a request, and a server answers each request with a response. The server may look in a place where it keeps things. That place is a database. A database is a repository of information that a server can pull content from to build a page or screen.

Here are two dates to remember. The iPhone first appeared in 2007. Apple opened its App Store in 2008. Where do people find them? People get apps from an online app store. Take a moment to picture those two dates, one after the other, and think about each one on its own. Say them out loud if you like. Then read on to see what comes next, and where a person goes to get one.

Now think about what one can see. An app can ask for permission before it uses the camera or contacts on a phone, and you can say Allow or Deny. Apps may ask for permission to use information on a device, such as contacts, calendar entries and location. You are not stuck with the first answer you gave. A phone's settings let a person change an app's permissions after they first answered. Here is one more thing to know. Some share information from a phone with other companies that show ads based on a person's location and interests. Take a moment to think about that, and then read on.

Here is a question that many people ask when they first get a phone. Is every one of them free? No. Some apps and some things inside apps cost real money. It is good to know this before you tap. There is a name for one kind of cost. In-app purchases let a person pay for extra things inside an app, so a tap can lead to a bill. Always look before you tap, and think about it for a moment, because a tap on the screen can be a way to spend money.

Here is a question about updates. Updating one gives you the latest features and makes it more secure. A phone can be set to update its apps automatically, with no tap at all. Here is why that matters to the people who make them and to the people who use them. Many software updates are made to fix security risks. There are harmful programs out there too, and they have a name. Malware is software made on purpose to cause harm.

Before you get an app, ask a grown-up. Parents can set up a phone so that a child has to ask a grown-up before getting an app. Some phones have settings that let a parent make a child ask permission before downloading or buying apps. Here is how a parent can tell which ones fit a child. Apps and games can have an age rating. Parental controls can block games and apps by their rating.

Words to know

• software: computer programs
• hardware: the equipment
• server: sending computer
• database: stored information
• malware: harmful software