function showContactForm() { document.getElementById("contactForm").style.display = "block"; } function hideContactForm() { document.getElementById("contactForm").style.display = "none"; } function validateForm() { var name = document.forms["contactForm"]["name"].value; var email = document.forms["contactForm"]["email"].value; var message = document.forms["contactForm"]["message"].value; var error = ""; if (name == "") { error += "You must enter your name.\n"; } if (email == "") { error += "You must enter your email address.\n"; } if (message == "") { error += "You must enter a message.\n"; } if (error != "") { alert(error); return false; } } <form id="contactForm" action="/action_page.php" style="display

# Version control

* Git
  * A version control system for tracking changes in source code during software development
  * It is primarily used for coordinating work among programmers, but it can be used to track changes in any set of files
* GitHub
  * A web-based hosting service for version control using Git
  * It is mostly used for computer code

# GitHub

## Create a repository

To create a new repository:

1. In the upper right corner, next to your avatar or identicon, click  and then select New repository.

2. Name your repository hello-world.

3. Write a short description.

4. Select Initialize this repository with a README.

## Forking

1. On GitHub, navigate to the main page of the repository.
2. Under the repository name, click Fork.

## Pull Requests

1. On GitHub, navigate to the main page of the repository.

2. Under your repository name, click  to clone your repository in Desktop.

3. Make some changes to the file you just cloned.

4. In