The Join tool is not used when in Edit Mode, but in Object Mode instead. You can select two different objects and join them so they become a single object. This is the opposite of the Separate tool (discussed later in this chapter).
To use the Join tool:
1. In Object Mode, select two or more objects. Determine the object you want to keep as the primary one and select it last to keep it as the active object. Attributes such as the center of the resulting object or its modifiers will be taken from the active object before using the Join tool.
2. Press Ctrl + J to join them into a unique mesh.
Tip
Join and Separate are similar to the Attach and Detach options in 3ds Max.
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