Definitions
Git and GitHub are tools used by developers worldwide for personal and professional software projects. Git is a popular version control system, developers can work together from anywhere in the world, can see the full history of the project and can revert to earlier versions of a project. Git is not the same as GitHub. GitHub makes tools that use Git. GitHub is the largest host of source code in the world.
Git is a distributed version control system that tracks changes in any set of computer files, usually used for coordinating work among programmers collaboratively developing source code during software development.
GitHub is an Internet hosting service for software development and version control using Git. GitHub is a website and cloud-based service that helps developers store and manage their code, as well as track and control changes to their code.
Version Control is a class of systems responsible for managing changes to computer programs, documents, large web sites, or other collections of information.
Repository is the centralized storage location for software packages. A repository can be local (personal computers) or remote (cloud repository like github repositories).
Commit record changes to the repository. Commits are created with the git commit command to capture the state of a project at that point in time, describing the change, author, date and unique identifier (SHA or Hash).
There are three core areas to git. These are the Working Tree, the Staging Area (also known as Index), and the Local Repository. When working in a git repository files and modifications will travel from the Working Tree to the Staging Area and finish at the Local Repository.
The Working Tree: is the area where you are currently working. It is where your files live. This area is also known as the “untracked” area of git. Any changes to files will be marked and seen in the Working Tree. If you make changes to files in your working tree git will recognize that they are modified.
The Staging Area: is when git starts tracking and saving changes that occur in files. These saved changes reflect in the .git directory. That is about it when it comes to the Staging Area.
The Local Repository (.git directory): is where Git stores the metadata and object database for your project. This is the most important part of Git, and it is what is copied when you clone a repository from another computer.
Branch is effectively a pointer to a snapshot of your changes. When you want to add a new feature or fix a bug you spawn a new branch to encapsulate your changes.
Merge join two or more development histories together.
Clone it is clone a repository into a new directory.
Origin it is the default name Git gives to the server you cloned.
Pull incorporates changes from a remote repository into the current branch. Command used to download the content from a remote repository to a local repository.
Push updates remote refs using local refs, while sending objects necessary to complete the given refs. Command used to push changes made from a local repository to a remote repository.
GIT Docs https://git-scm.com/book/es/v2