Cornifer

Cornifer is first encountered in the bottom of The Forgotten Crossroads where he sells you a map and points you towards his wife Iselda's shop up in Dirtmouth.

Finding Cornifer in each area is essential for unexplored areas.

Sells

 * Map for Forgotten Crossroads: 30 Geo

Map
To start mapping an area, you first need to purchase the map from Cornifer. That will allow you to see the uncompleted map of the area. To complete the map, you then need the Quill, sold by Iselda.

The Wayward Compass charm show your location on the map.

Different pins can also be acquired that shows different points of interest on the map.