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 (sometimes confused with Foreward or Prologue) — A very rarely included section that details why you are qualified to write about your topic of your thesis or why you became interested in the topic (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 what can be included in these sections. Note: If your dedication is short (like "To my parents"), you may choose not to include the "Dedication" heading at the top of the page. A demonstration of how to format the dedication page this way is shown below.