What does a filesystem do?

Now that we've looked at the components of a filesystem, we need to understand the basic functionality. A filesystem is a way of organizing data (the hierarchical nature of directories, and the fact that directories and data elements have names), as well as a way of storing data (the fact that the data elements contain useful information).

There are many types of filesystems. Some let you create files and directories within the filesystem, others (called read-only) don't. Some store their data on a hard-disk, others might manufacture the data on-the-fly when you request it. The length of the names of data elements and directories varies with each filesystem. The characters that are valid for the names of data elements and directories vary as well. Some let you create links to directories, some do not. And so on.