Meaning of the word "fly on the wall" in English

What does "fly on the wall" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

fly on the wall

US /flaɪ ɑn ðə wɔl/
UK /flaɪ ɒn ðə wɔːl/
"fly on the wall" picture

Idiom

a person who observes a situation without being noticed or involved

Example:
I'd love to be a fly on the wall during their secret meeting.
The documentary offered a fly on the wall perspective of the band's tour.