ArcMap: Define Projection vs Project Tool

How & when to use Define Projection tool versus Project Tool, with background info about geographic data (geographic coordinate systems and projections) to understand what these tools do in ArcMap. Part 1: Background Understanding geographic data (Geographic coordinate systems, projections, and GCS/PCS): 0:18 How ArcMap behaves (data frame coordinate system, projecting on the fly): 1:38 Project tool vs. Define Projection: 2:58 Part 2: Doing it in ArcMap Unknown Spatial Reference warning 4:00 Using the Define Projection tool 4:36 Data Frame Properties & Geographic Coordinate Systems warning 6:20 Using the Project tool 8:36 Recap: 11:30