This is the 10127th most frequent Korean word.
관객에게
"To the audience" or "toward the audience."
In this sentence, '관객에게' (to the audience) indicates the direction of the action ('인사를 했어요', greeted) towards the audience.
극장에서 배우가 관객에게 인사를 했어요.
The actor greeted the audience at the theater.
Here, '관객에게' specifies the recipient of the emotions being conveyed ('감동을 주는', moving) through the performance.
음악회에서 관객에게 감동을 주는 연주를 준비했어요.
At the concert, I prepared a performance that would move the audience.
In this case, '관객에게' denotes the target group ('소개했습니다', introduced) to whom the book is being presented.