shadowing
n.the process of following someone closely to learn how they do their job. In computing, it also means when a program runs in the background while you use another one.
n.the practice of following a more experienced professional to observe and learn their techniques. In a technical context, it refers to the execution of a process or thread in the background while the foreground process remains active.
“The new nurse is shadowing the senior doctor today.”
“During the first week of the internship, the student spent several hours shadowing the lead engineer to understand the workflow.”
“The operating system employs shadowing to allow the user to continue working on a document while the background process handles the complex rendering of the final layout.”
From shadow (verb) + -ing (suffix forming nouns denoting the act of doing something, an action, or the embodiment of an action; or forming present participles of verbs).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.