What is the purpose of an instructional coach?

For Professional Learning Communities:

Across content areas, classrooms in which students are engaged, motivated, working hard , and stretching themselves have teachers who consistently employ similar instructional practices. An instructional coach provides professional learning communities with instructional leadership that helps teachers analyze student learning and gives teachers the research-based skills and tools they need to incorporate these highly effective practices to facilitate visible learning everyday, in every class, with every student.  

For Individual Teachers:

An instructional coach provides individual teachers with a collaborative partner who helps define and achieve student-centered goals that optimize instructional time and create balance in and out of the classroom for the teacher and the students.