PowerPoint has a smart little-known feature built in: presenter view. The screen on your laptop is different from the full-screen view the audience sees.
- Slide count
- Current slide
- One slide back
- Opens a menu (black screen, white screen, other functions)
- Next slide
- Presentation timer
- Slide sequence
UPDATE: From the comments below, John Goalby is pointing to his very detailed, free ebook on the subject of Presenter View.