GitFLow is a fairly widespread organization of Git repositories that segregates things properly and therefore collaborates with a large number of people.
Dedicated tools for Git have been created to allow greater work ease in merges, commits and passages between different branches.
If the branch organization is common to all people using the repository, the use of GitFlow tools is by no means mandatory. You can easily navigate through a GitFLow managed repository using Git's simple tools. Or mix the two. Using dedicated tools is a personal choice, which will only affect your local repository. They were just designed to facilitate work in a such configuration.
GitFlow is based on a clear hierarchy of branches, which avoids unwanted commits on the main branches. The idea is to make clear additions of features, and to maintain stable states on the main branches.
There are generally several basic branches in a project(managed according to the GitFlow model):
The branches shown in this picture:
Grafikart offers a video of presentation of GitFlow, as always of excellent quality.