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Module 2: GitHub, Repositories, and SSH Keys

Git can work entirely on your computer. GitHub is an online platform for hosting Git repositories, reviewing code, and collaborating with a team.

Git and GitHub are different​

GitGitHub
A version control tool installed on your computerA website and service that hosts Git repositories
Can create commits without an internet connectionRequires a network connection for push, pull, and online collaboration
Manages file versions and branchesAdds Pull Requests, Issues, Actions, and other collaboration features

Step 1: Register a GitHub account​

Skip this step if you completed it in Module 1.

  1. Go to GitHub.
  2. Select Sign up.
  3. Enter your email address, password, and username.
  4. Complete email verification.

You should also enable two-factor authentication (2FA) so the account is protected by more than one password.

Step 2: Create your first repository​

  1. Sign in and open New repository.
  2. Enter git-practice-remote for the repository name.
  3. For your first exercise, you can choose Private.
  4. Turn on Add README.
  5. Select Create repository.

After the repository is created, become familiar with these common areas:

AreaPurpose
CodeBrowse files, commits, and branches
IssuesTrack requirements, problems, and discussions
Pull requestsPropose, review, and merge changes
ActionsRun automated tests or deployment workflows
SettingsManage permissions, branch rules, and repository settings

GitHub updates its interface regularly. If a button is in a different location, look for a feature with the same name.

Clone, Fork, and Download ZIP​

OperationKeeps Git history?Common use
CloneYesDevelop locally and synchronize changes over time
ForkYes, and creates a copy in your GitHub accountContribute to a project where you do not have write access
Download ZIPNoGet the current files without future synchronization

Step 3: Create an SSH key​

An SSH key consists of a pair of keys:

  • The private key stays on your computer and must never be shared.
  • The public key can be registered with GitHub.

First, check whether your computer already has keys:

ls -al ~/.ssh

If you do not have id_ed25519 and id_ed25519.pub, create a new key:

ssh-keygen -t ed25519 -C "[email protected]"

Respond to the prompts as follows:

  1. Enter file in which to save the key: press Enter if you do not already have a key at the default location.
  2. Enter passphrase: enter a secure passphrase for the key.
  3. Enter the same passphrase again.
Do not overwrite an existing key

If the terminal says the target file already exists, answer n. Follow the official GitHub instructions to create a key with a custom name instead.

Step 4: Add the private key to ssh-agent​

macOS / Linux / Git Bash​

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

On macOS, follow GitHub's official instructions to store the passphrase in Keychain:

ssh-add --apple-use-keychain ~/.ssh/id_ed25519

Step 5: Add the public key to GitHub​

Display your public key:

cat ~/.ssh/id_ed25519.pub

Copy the entire line that begins with ssh-ed25519, then:

  1. On GitHub, select your profile picture → Settings.
  2. Select SSH and GPG keys.
  3. Select New SSH key.
  4. Enter a recognizable title, such as home-laptop.
  5. Paste the public key into the Key field and add it.

Step 6: Test the SSH connection​

ssh -T [email protected]

The first connection may ask whether you trust GitHub's host. Verify that the host shown is github.com, then enter yes. A successful response includes your GitHub username and a successful authentication message.

Step 7: Clone the repository over SSH​

On the GitHub repository page, select Code → Local → SSH and copy a URL similar to this:

[email protected]:YOUR_ACCOUNT/git-practice-remote.git

Return to your terminal:

cd ..
git clone [email protected]:YOUR_ACCOUNT/git-practice-remote.git
cd git-practice-remote
git remote -v
git status

Replace YOUR_ACCOUNT with your GitHub username. The origin shown by git remote -v is the default remote linked to this local repository.

Security checklist​

  • Safe to share: the contents of the id_ed25519.pub public key.
  • Never share: the contents of the id_ed25519 private key.
  • Never commit passwords, API keys, or .env files to Git.
  • If you are unsure about an SSH command or host fingerprint, stop and verify it before accepting anything.

Further reading​