What Git and GitHub Are, and Getting Set Up

The problem Git solves

You have probably had a folder like this:

project.py
project_final.py
project_final_v2.py
project_final_v2_REALLY_final.py

Which one is the real one? What changed between them? If something broke, which version worked? Now imagine five people working on the same project, each with their own copy.

Git fixes this. It is a version control system: it keeps one copy of your project, and records every change you choose to save as a commit, with a message describing it. You can see the full history, compare any two versions, go back when something breaks, and let many people work on the same project without overwriting each other.

Git is used by almost every software team, data team and web agency in the world. Not knowing it is like not knowing how to use email at work.

Git vs GitHub

They are related but different, and beginners often mix them up.

A project tracked by Git is called a repository, or repo. When you put a copy on GitHub, anyone you allow (or everyone, if it is public) can see it. Other websites do the same job as GitHub, such as GitLab and Bitbucket, and they all use Git underneath.

How Git thinks: three places

To use Git well, you need one picture in your head. Your files live in three places, and Git moves changes between them on your command.

  Working folder        Staging area         Repository
  (your files)    -->   (the next commit) -->  (the history)

     edit files        git add <file>        git commit -m "message"

1. Working folder. The normal files you open and edit.
2. Staging area (also called the index). A waiting room where you choose exactly which changes go into the next commit.
3. Repository. The saved history: a chain of commits.

The staging area surprises beginners, and it is worth it. It lets you change five files, but commit them as two clean, separate pieces of work, each with its own message.

What a commit is

A commit is a snapshot of your whole project at one moment. Each one has:

• A unique ID (a short code like a3f9c21).
• A message saying what changed.
• An author and a time.
• A link to its parent, the commit before it. These links make the chain, which is the history.

A branch is just a movable label pointing at a commit. The default one is called main. You will learn branches in lesson 5.

Key words

Meet the terminal

Git's real power is in the terminal (also called the command line), a window where you type commands instead of clicking. It looks old-fashioned, and it is faster, works the same everywhere, and is what professionals and every tutorial use. A command is a word, then some options:

git status          the command git, with the sub-command status
ls                  list the files here
cat notes.txt       show what is inside a file

On your computer you open it with Git Bash (Windows, installed with Git), Terminal (Mac), or the terminal in VS Code. You do not need to install anything to learn here. The practice terminal below works the same way, with a small project folder to experiment in.

Try the practice terminal

In this course, you practise real Git commands in a practice terminal built into the page. On the left are the files of a small project, and you can click one to read and edit it. On the right is the terminal. Try these, one at a time, and press Enter after each:

1. ls to list the files
2. cat notes.txt to read one
3. git --version to check Git is there
4. help to see which commands the practice terminal knows

Nothing you do here can break anything. If you get lost, press Reset.

Install Git on your computer

When you are ready to use Git for real:

1. Go to git-scm.com/downloads and install Git for your system. On Windows, accept the defaults. This also installs Git Bash.
2. Open Git Bash (or Terminal) and type git --version. You should see something like git version 2.45.0.

Tell Git who you are

Every commit records who made it, so the very first thing to do on a new computer is set your name and email. This only needs doing once:

git config --global user.name "Ada Okafor"
git config --global user.email "ada@example.com"

Use the same email as your GitHub account, so GitHub links your commits to your profile. Without a name and email, Git refuses to make a commit. Try it yourself in the task below.

Set up your GitHub account

1. Go to github.com and sign up with an email you will keep after graduation.
2. Choose a professional username, such as adaeze-okafor or tundeanalytics, not cooldude2005. It appears in your links.
3. Add a profile photo and a one-line bio ("Economics student · learning Python and SQL").
4. Turn on two-factor authentication in Settings, then Password and authentication.

Try it

First, tell Git who you are, in the practice terminal. It starts with no name and no email set.