Maps can be displayed in any coordinate system. The map is displayed in the coordinate system defined as the Target Coordinate System for the map. A coordinate system normally has a defined projection and datum. If some map layers are using a different source coordinate system than the map's target coordinate system, the map layer is converted to the map's Target Coordinate System. The map's Target Coordinate System is the new coordinate system that you want to use to project your X, Y coordinate data.
The Coordinate System page is located in the Property Manager when a Map object is selected.
Specify the map coordinate system on the Coordinate System page.
Click the Change button next to Coordinate System to open the Assign Coordinate System dialog. This dialog lets you set the desired target coordinate system. This is the coordinate system in which you want the map to be displayed.
If the map has custom limits and an unreferenced coordinate system, changing the coordinate system will change the map limits to the default limits.
If the map has custom limits and is currently referenced, changing the coordinate system will not change the map limits to the default limits. Instead, the axis limits are converted to the new coordinate system and properly limited in the new coordinate system.
Map Coordinate System Overview
Introduction to Common Map Properties
Assign Coordinate System Dialog
Introduction to Map Projections
Introduction to Map Layers
Source Coordinate System - Map Layer