Using the Join command, you can join different curves that are collinear or connected end-to-end into a single curve. To explain the join command, I will use the three drawings shown here:

In the following example, we will join these drawings together and we will also merge the gaps that exist in these drawings:

1. Start the Join command from the expanded Modify panel in the Home tab or use its command alias, J:

2. Now, the command line will prompt you to select the source object or multiple objects that you want to join. In this case, select two lines, as the ones labeled A in figure 3.80, and press the Enter key.

3. You will notice that not only do the lines join to fill the gap, but they also merge to become a single line, too.
4. Now, we will merge the gap in the arcs labeled B in figure 3.80. Once again, select the join tool and then click on the arc on the left and then the arc on the right and press Enter.
5. You will notice that now the arc gap is merged in an anticlockwise direction, starting from the arc selected first.

In this case, the gap at the bottom will be merged in an anticlockwise direction and moves from the arc to the left to the arc to the right. If, however, you select the arc to the right first and then the arc to the left next, then the gap at the top will be merged:

The C shape in figure 3.80 is made of three connected curves—two lines and one arc—which are connected from end to end. If you use the join command on these three curves, you will end up with a single polyline. So, you can use the join tool to connect the curves into a polyline or spline.