Dynamic data exchange (DDE) is a protocol Windows provides for inter-process communications.

Using this protocol, two applications communicate in a client/server relationship in which the client initiates the communications and the server exchanges data with and provides services to the client. This is a very flexible IPC mechanism that enables a range of capabilities from simple data transmission between two applications to the ability for multiple applications to "work" in each other's environments. For example, a word processing application might create and modify spreadsheets in a spreadsheet application, and the spreadsheet application might, in turn, create and modify documents in the word processing application.