Dedication, Acknowledgements, and Preface sections are all optional pages. But, what is the difference between these three?
Dedication — A personal tribute to someone or a group of people. Example: "To my parents."
Acknowledgements — A professional tribute to a person or people who helped you with the thesis. Example: "I wish to thank my thesis advisor for the hours of help in the lab making sure the experiments were set up properly and guiding me through the thesis process."
Preface (also called Forward or Prologue) — A very rarely included section that details why you became interested in the topic of your thesis (for example, an anecdote about a childhood incident that led you to become interested in the topic). Do not confuse this with the literature review; this is more of a personal story.
The video below gives more examples of some possibilities of what can be included in these sections.