guide

noun

• Someone who guides, especially someone hired to show people around a place or an institution and offer information and explanation.

  "The guide led us around the museum and explained the exhibits."

• A document or book that offers information or instruction; guidebook.
• A sign that guides people; guidepost.
• Any marking or object that catches the eye to provide quick reference.
• A device that guides part of a machine, or guides motion or action.
• A spirit believed to speak through a medium.
• A member of a group marching in formation who sets the pattern of movement or alignment for the rest.