What is the significance of tessitura in music theory and how does it impact vocal performance?

Tessitura in Music Theory refers to the range of notes that a vocal or instrumental part typically lies within. It is significant in vocal performance because it determines the comfort and ease with which a singer can perform a piece. Singers with a tessitura that suits their voice well will find it easier to sing with control and expressiveness, while those with a tessitura that is too high or too low may struggle with pitch accuracy and vocal strain.