Collecting requirements for a project

What is involved in collecting requirements for a project? Why is it often such a difficult thing to do? There are many ways to manage the scope of a project. The text mentions several. Which ones do you think are the most effective? Do you think these techniques protect the project from "scope creep"? Why is project scope management so challenging in IT projects and what suggestions do you have for preventing or managing scope creep? What is your opinion of scope creep after reading this chapter, should it be prevented?