The Git System and GitHub Platform

Git  

Git is nothing else than a "version control system" which allows us to monitor and control the software's development. This system has been widely accepted and implemented by many companies like: Google, Facebook, Microsoft, Twitter, among others as stated in its webpage.

The main idea behind Git is the development of an idea inside a repository, which can be modified by many contributors in different branches. In that sense we can define the following:

Repository.- Es como una carpeta donde se alojan los archivos correspondientes a un proyecto.

Contributor.-Any person who is involved in the development of the project.

Branch.- Es una versión distinta de la general y se deriva de la branch master. Cada branch, que no sea master, posee otras características de código, por tanto, una branch sería un escenario donde puedes realizar otro tipo de evaluaciones, funciones, etc.
Una vez que este listo el contenido en la branch se realiza el "pull request"

Moreover, there are some operations that allow the contributors to develop the project:

• Pull request.- Se define como la combinación de la branch donde se trabaja con el master.

GitHub

GitHub, on the other hand, is a company which implemented massively Git. Although the GitHub's service has some cost when it comes to private repositories, there are a lot of projects hosted on GitHub which use the free version of the service.

Management of Git comes easy when we take the GUIs programs developed by Git or GitHub. In the first case, Git may be downloaded from here, and in the second one, GitHub Desktop may be downloaded from here. Both programs are easy to handle and answer specifically to the same concept.

References.- In case you want to know more:
Git -
GitHub -