Deployment diagrams show the physical layout of various hardware components (Nodes) that compose a system as well as the distribution of executable programs (software components) on this hardware.
Deployment diagrams are crucial when dealing with distributed systems. You may show the actual computers and devices (Nodes), along with the connections they have to each other, thus specifying a system topology. Inside the Nodes, executable Components and objects are located in a way that it shows where the software units are residing and on which Nodes they are executed. You may also show dependencies between Components.
As of MagicDraw 17.0.1, the Deployment diagram (or the Component diagram) replaces the Implementation diagram, which is no longer supported in UML standard. An Implementation diagram created with earlier versions of MagicDraw, now opens as
Deployment diagram, if Nodes were used in the Implementation diagram
Component diagram, if Nodes were not used in the Implementation diagram
Customized diagrams that were based on the Implementation diagram are now based on the Component diagram.