(1) Not proprietary. See
open architecture,
open system and
open source. Contrast with
closed architecture and
closed system.
(2) To "run" a program (application). Open means "load the program and run it" or "launch the program and run it."
(3) To engage a digital file. From the user's point of view, open also means to read the first block of data. From the programmer's standpoint, open is the first step, and "read the first block of data" is the next. Contrast with
close.
(4) To open a switch means to stop or halt the current from passing through. The switch is then considered "off." See
switch.