An instance of a software

[hhtt21]

I cannot understand the meaning of instance used as to computing?

Here is an example sentence: OpenFOAM runs on Windows inside a virtual Docker environment. I would guess that there is already an instance of Docker running.

https://www.physicsforums.com/thread.../#post-5727717

Thank you.

[GoesStation]

If you run one program twice and both copies are running at the same time, you have two instances of the program.