How are budgets useful in the planning of a business?

Two different questions: 1 paragraph for each 

1. How are budgets useful in the planning of a business? Discuss one type of budget presented in the lecture and explain how that budget contributes to the planning process.

Book information:  Managerial Accounting- Jiambalvo, James (2013, 5th Edition) John Wiley & Sons, Inc. ISBN 978-1-118-07876-1. Chapters 9 and 10 (Please make sure you can access the book before biding)

2. What is zero-based budgeting? How can this type of budgeting assist in the planning process? What are some disadvantages of zero-based budgeting?