Meaning of the word "sit in on" in English

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

sit in on

US /sɪt ɪn ɑn/
UK /sɪt ɪn ɒn/

Phrasal Verb

to attend a meeting, class, or discussion as an observer, without actively participating

Example:
I'm going to sit in on the marketing team's meeting today to learn more about their strategies.
The student asked if she could sit in on the advanced philosophy class.