Real time code collaboration
If you give other Codio users permissions to access to your project, then Codio allows more than one user to view and edit files simultaneously.
Rather like Google Docs, you will be able to see other people editing the file in real time.
Because of this collaboration feature, your files are saved in real time and there is no need to press the save button. It just happens automatically.
You can change full access to your project from the Project->Permissions menu, but this is risky and we advise strongly against this unless you are sure only one person will be editing the project at a time.
The better approach is to use Git. If you are familiar with Git then each person has their own project but they all use Git to synchronize the content with a remote repository hosted on a platform like GitHub or BitBucket.