A computer system that allows for multiple users that each have access to shareable files. In one exemplary embodiment, each user has a user file tree that corresponds to the shareable file tree and initially contains links or pointers to selected shareable files. Each user also has a private file area to store files. If a user wishes to access a shareable file to perform an action that does not modify the shareable file, then the user file tree will point to the shareable file and allow the user to access the file. On the other hand, if the user wishes to access a shareable file and perform an operation that modifies the shareable file, the computer system will make a copy of the shareable file and place the copy in the user's private file area. Next, the computer system will modify the user's file tree such that the link that pointed to the shareable file now points to the copy of the shareable file that was placed in the user's private file area. The user is then able to access the copy and may modify the copy. Because each user's private file area is not publicly available, any changes made by this user are not visible to any other user.