To engage a file for reading and writing. Technically, an app is "run" and the data file is "opened." For example, after a word processing application is "loaded and run," a document is "opened" for editing or printing. Then, the document is "closed," and the app is "exited." Apps are also said to be "opened" and "closed."
In the case of a script or batch file, "open" can mean "open" for editing or "open and run." The difference is significant. Opening a batch file to edit its contents causes no action until the user makes changes, whereas opening and running a batch file causes instructions to be executed. Contrast with close
To "run" a program (application). "Open" is increasingly used to mean "load and run."
With regard to a switch, open is "off." See switch
Made to operate or function compatibly with other products. See open architecture
, open system
and open source