What is the difference between a repository and a project?

[Franklin Siu]

I'm not sure what is the difference between a project and repository.  If I have several unrelated websites, do I create 1 project and multiple repository or do I create a project for each website with 1 repository?  

[Vasiliy Zverev]

Project is a container for repositories. 

It is used to:

1. Group similar repositiries
2. Grant permission for all repositionries.

If you need to have the same read/write permission for set of sites - organise it into a single project.

If you going to store something else but websites on this instance - group all sites into a project.

[kim92se]

good explain !