1. Resolution: The number of pixels per square inch on computer generated display; the greater  the resolution the clearer the picture.
  2. Discrete Data: Data that can only take certain values. For ex. The number of students in your class.(You can’t have half a student).
  3. Triangulation: A technique  for establishing the distance  between any two points, or the relative postion of two or more points, by using such points as  as vertices of a triangle  or a series of tringles, such that each triangle has a side of know or measurable length(base or baseline) that permits the size of the angles  of the triangle or length  of its other two sides to be established  by observations taken either upon or from the the two ends of the baseline.
  4. Break Lines: A line used to describe the boundary of an imaginary broken-out section or to shorten dimensions that are excessively long. Break lines are wavy and irregular.
  5. Z- Values: Usually the reference to the value of surface height in a DEM.  at a particular X,Y location.
  6. Nodes: Represents change in elevation and direction.
  7. Slope: Is a measurement  of how steap the ground surface is.
  8. Aspect: Orientation of each surface element(direction).
  9. Elevation: Is the height above a fixed reference point.
  10. Tessellated space: No gaps or over lays.