Directories and files are stored in a file system. Each file system contains exactly one directory at the very top level, called the
<firstterm>root directory
</firstterm> for that file system. This root directory can contain other directories. One file system is designated the
<firstterm>root file system
</firstterm> or
<literal>/
</literal>. Every other file system is
<firstterm>mounted
</firstterm> under the root file system. No matter how many disks are on the FreeBSD system, every directory appears to be part of the same disk.