Button

What is a "Button" in the Computer?

A button in the computer can mean either a physical button part of the hardware or a digital, graphical button on the screen that's part of a graphical user interface (GUI), which when pressed performs some operation.

What are Hardware Buttons?

A typical computer has the following hardware buttons:

1. The power button on the computer tower, which turns the computer on and off. While the computer is turned on, pressing it once tells the operating system to shut down. If the operating system is not responding (the PC is frozen), you can press and hold the power button for a few moments to forcefully power off the computer. This has the same effect as unplugging it from the power outlet, so it can damage your operating system if it's updating, corrupt your applications, lose the data of your unsaved files, etc.
2. The reset button (power-wise), which does the same thing as the above. This button isn't common nowadays.
3. The mouse buttons: the left mouse button and right mouse button (also called primary mouse button and secondary mouse button). And the scroll wheel in the middle, which is also called the middle button. Some mouses also have more than 3 buttons.
4. The power button on other hardware components, such as the power button on the monitor, the speakers, the router, etc.
5. The reset button on other hardware components. This one means "reset" as in "restore factory settings." Some routers have these. The problem is that in order to configure the router you need to know the administrator password of the router, and if you reset it, it's reset to the factory setting, which may or may not be written on the router or in its manual. Some routers have their MAC address as the default password, which is easy to find out, which is convenient, and also means they're also easy to hack into, which is unsafe.

The buttons on the keyboard are called "keys," not "buttons." I do not know why they are called keys. I suppose it's not a "buttonboard," but what is the difference, really?

What are Graphical Buttons?

Graphical buttons, digital buttons, or virtual buttons, are buttons displayed on the screen of the computer that are part of a graphical user interface. When these buttons are "pressed," they are activated and trigger some function of the program. What happens when they are pressed varies from program to program, so they tend to have a text label or an small image (called an icon) that identifies the purpose of the button.

Note: if a button only has an icon, placing the mouse cursor over the button (i.e. hovering it) for a few moments should reveal a tooltip that explains what the button does. If the application has a statusbar, there may also be some hint of what the button does displayed in the statusbar. An application that doesn't have tooltips in its unlabeled icon buttons is a bad application.

To "press" a graphical button, one would normally use the mouse: place the mouse cursor over the button (i.e. hover it), then press the left mouse button, and release it while the cursor is still over the button. This is called a "click." Note that if you press the left mouse button and then move the cursor away from the button, the button will not activate, i.e. it will be "cancelled."

Normally, graphical buttons have a tridimensional appearance and they will graphically appear pressed while the mouse button is pressed. Nowadays many interfaces have "flat" designs where buttons change colors instead.

It's also possible to press any graphical button of a well-made application without using the mouse by navigating to it using the Tab key to cycle keyboard focus and then pressing the Enter key while the button has the keyboard focus.