DLL injection is a technique used to run code within the address space of another process by forcing it to load a dynamic-link library(DLL).
DLL injection is often used by external programs to influence the behaviour of another program in a way its authors did not anticipate or intend. For example, the injected code could hook system function calls, or read the contents of password text-boxes, which cannot be done the usual way. A program used to inject arbitrary code into arbitrary processes is called a DLL injector.
