What Is a Terminal?

A terminal is an application that lets you control a computer by typing text commands. It may also be called a “command line,” “shell,” or “CLI” (Command Line Interface).

The Difference Between GUI and Terminal

There are two main ways to operate a computer.

A GUI (Graphical User Interface) is a way of using icons and buttons with a mouse. Opening folders in Finder or clicking menu items in an app are GUI actions.

A CLI (Command Line Interface) is a way of operating by typing text commands. The terminal is the most common example.

Thinking of It as a Restaurant Waiter

The difference between GUI and CLI is easy to understand if you compare it to ordering food in a restaurant.

• GUI is like “looking at the menu and ordering by pointing.” It is intuitive and easy to start with, but you cannot ask for something that is not on the menu.
• CLI is like “speaking directly to the waiter.” You need to learn the words at first, but you can make custom requests that are not on the menu and send several orders at once.

Once you can use the terminal, you can complete tasks that would take dozens of clicks in a GUI with a single command line.

How to Open the Terminal on Mac

Macs come with a built-in Terminal app.

Recommended: use Spotlight Search

1. Press Command (⌘) + Space
2. Type Terminal
3. Press Enter when the Terminal app appears

Using Finder

1. Open Finder
2. Go to Applications -> Utilities -> Terminal and double-click it

Tip: Because you will use the terminal often, it is convenient to keep it in the Dock. Right-click the Terminal icon in the Dock and choose “Keep in Dock.”

Reading the Prompt

When you open the terminal, you may see something like this:

username@hostname ~ %

Here is what each part means:

Part	Meaning
username	The name of the currently logged-in user
hostname	The name of the computer
~	Your current location. ~ means the home folder
%	The shell is waiting for a command. Some shells use $ instead

If the cursor is blinking after % or $, the terminal is ready for input.

Why Engineers Use the Terminal

It Can Be Automated

Tasks that you repeat by hand in a GUI can be saved as scripts and run again and again in the terminal.

It Is Fast

Once you get used to typing commands, it becomes much faster than moving the mouse and clicking around.

It Works Well With AI Tools

In 2026, many AI tools run in the CLI. When you ask Claude Code to “organize the files in this folder,” it runs terminal commands to do the work. If you understand the terminal, you can follow what the AI is doing and work with it more effectively.

It Is Essential for Servers and Cloud Environments

Production servers usually do not have a GUI. Terminal skills are a core engineering skill.

Why It Matters in the AI-Native Era of 2026

The following tools all run in the CLI:

# AI coding assistance
claude

# GitHub operations
gh pr create
gh repo clone

# Package installation
npm install
pnpm add

# Version control
git commit -m "add feature"

# Mac tool management
brew install git

To use these tools well, you need the basics of the terminal. In other words, learning the terminal lets you get the most out of AI productivity gains.

How to Stop Being Afraid of the Terminal

The first time you see a terminal, the black screen and flowing text may feel intimidating. But keep the following in mind:

• Nothing happens until you press Enter. Typing a command does nothing by itself. If you are unsure, press Ctrl + C to cancel.
• Most mistakes can be fixed. Even if you delete a file, it can often be restored.
• Error messages are not the enemy. If an error appears, search the message as it is or paste it into Claude and ask for help.
• Practice makes it familiar. The first few days may feel hard, but after a week it will start to feel natural.

On the next page, try entering actual commands and experience how the terminal works.

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Next: Basic Commands