[[Image:Some_X_windows.svg|thumb|An example of a multiple document interface layout]]
In [[graphical user interfaces]], aA '''multiple document interface''' or ('''MDI''') is onea whose[[graphical user interface]] in which multiple windows reside under a single parent window. Such systems often allow child windows to embed other windows inside them as well, creating complex [[Hierarchy#Nested hierarchy|nested hierarchies]]. This contrasts with [[single document interface]]s ('''SDI''') where all windows are independent of each other.
