3.3 Some key concepts

Before manipulating mapping / GIS tools, we insist on being aware of and referring to the concepts presented below. If they are not all used in some mapping software such as Google Earth, they remain essential to understand how the tools work. It is also a prerequisite to learn the QGIS tool via the tutorial presented in Part Six.

In this section, you will discover the key concepts of GIS such as :

• 3.3.1 The layers
• 3.3.2 The attribute table
• 3.3.3 Vector and raster data
• 3.3.4 Geometries
• 3.3.5 Coordinates, coordinate systems and projections