[1] Examples of code mobility include scripts downloaded over a network (for example JavaScript, VBScript), Java applets, ActiveX controls, Flash animations, Shockwave movies (and Xtras), and macros embedded within Microsoft Office documents.
For example, the ILOVEYOU, TRUELOVE, and AnnaK emails viruses/worms all were implemented as mobile code (VBScript in a .vbs email attachment that executed in Windows Scripting Host).
In almost all situations, the user is not aware that mobile code is downloading and executing in their workstation.
This is specially relevant to the mobile devices being developed which are cellular phones, PDAs, etc.
Instead of installing software packages, they can be "leased" and paid for on a per-usage basis.