In SOLIDWORKS, we can understand reference geometries as ones we can use as a base or reference for something else. For example, a plane is considered a reference geometry that we use as a base for sketches. A coordinate system is a reference geometry since we can use it as a base to determine specific locations within the canvas. In this section, we will learn what makes a coordinate system and how to define a new one in SOLIDWORKS. 

In our sketch creation process, we always link our sketch to the origin. The origin is the base point for our coordinate system, which extends through the three axes: X, Y, and Z. In the lower-left corner of the SOLIDWORKS canvas, we can notice the direction of the three axes:

Using the coordinate system, we can locate any point in the canvas according to its X, Y, and Z coordinates. When in sketch mode, the lower-right corner of the canvas will show us the location of the cursor according to the X, Y, and Z locations. The following screenshot highlights where we can find these coordinates:

Since SOLIDWORKS already provides us with a default coordinate system, why do we need additional ones? Here are two reasons why we may need a new coordinate system:

• To determine the coordinates according to a different coordinate system with different orientations: For example, if we measure the center of mass of an object, the measurement will be relative in X, Y, and Z locations for the default coordinate system. With additional coordinates systems, we can determine the center of mass according to a different coordinates system of our choosing. We will explore this later in this chapter.
• To switch our views of directions: In certain applications, we may need to redefine our axes to change our sense of direction as we are creating a model. Additional coordinate systems can help us accomplish that. Also, when working with different people in a specific design, pointing toward different coordinate systems can ease communication. 

We have just covered reference coordinate systems and why we may need additional ones for certain applications. Now, we will start learning how to define a new coordinate system within SOLIDWORKS.