Think of a branch on a tree. Stemming from that branch you have other branches, and from those branches more branches. Imagine each branch can have leaves. This is a fairly accurate representation of your file system under Windows and DOS. If I ask you to recursively examine the leaves of branch "X", then you would start at branch X and examine all of its leaves, you would then examine it's "children" branches or sub-branches, until you had visited every branch. Well - the branches are directories, the sub-branches are sub-directories, and the leaves are your files.