A syllabus is an academic document that communicates course information and defines expectations and responsibilities. There are seven essential components to an academic syllabus: Instructor information, General course information, Course objectives, Course policies, Grading and evaluation, Learning resources, and the Course Calendar.
Yes. Although it is not often, sometimes due to special occasion, syllabus can be changed. Usually the professors will be responsible to inform all of the students about the changes.
Many professors state that the syllabus is subject to change at the discretion of the professor. That is why many professors make you sign a form indicating that you have read the document and all willing to comply with the rules that are outlined.