The most common way people use GitHub is to share their code. All of the code that is public on the site can be downloaded to your machine and often ran with help of instructions in the 'readme' file.
Here's an example of a project that you can download and experiment with on your computer. EXAMPLE
What's even cooler is that you can allow your friends or colleagues to contribute their code to your project. You can even discuss the chunks of code that are sent up like you might discuss a photo on Facebook.
GitHub makes coding social.
A Pull Request is a feature from GitHub that allows you to write code and then request that the code to be 'pulled in' (accepted) into the project.
This is a really common way for people to collaborate in an orderly fashion where code is reviewed before it is accepted into the project.
However, the Pull Request's most amazing ramification is how you can contribute to Open Source projects. For example, somebody may have built an amazing project for converting currencies that you use in your application (for free since Open Source is free). You might have used a currency that the project did not support, like Bitcoin.
Instead of whining to the developers, you take it upon yourself to modify the project and add the functionality you need, you then open up a Pull Request to the developers with your Bitcoin support. Horray! You contributed to Open Source!
Inspired? As someone new to programming, you can contribute too. In the course of this class and your programming life, you will come across some really bad instructions in 'readme' files. Open Source projects notoriously have bad documentation.
Fix the instructions and then open up a Pull Request. The project's developers will love you for it.
GitHub's own GUI for Mac & PC is getting better and better. It is a welcome change from the command line Git program.
Although the Git command line tool is more powerful, for every day tasks, the GitHub GUI is all you need. This is great because it's much easier to use!