How Do I Join Two Closed Shapes in Illustrator?

To join two closed shapes in Illustrator, you can use the Pathfinder panel or the Shape Builder tool. Here's how:

Using the Pathfinder Panel

Select both shapes: Use the Selection Tool (V) to click and drag a selection box around both shapes you want to join.
Open the Pathfinder Panel: Go to Window > Pathfinder.
Choose a Pathfinder Option: In the Pathfinder panel, you have several options for combining the shapes. The most common ones for joining shapes are:
- Unite: This merges the shapes into a single shape, removing any overlapping areas. Click the "Unite" icon (the first icon in the top row).
- Merge: This combines the shapes and removes the stroked lines of overlapped shapes. Click the "Merge" icon.
- Other Pathfinder options: Experiment with other Pathfinder options like "Intersect," "Exclude," and "Minus Front" to achieve different results depending on how you want the shapes to interact.

Select both shapes: Use the Selection Tool (V) to select the shapes you want to join.
Select the Shape Builder Tool: Choose the Shape Builder Tool (Shift + M) from the toolbar.
Merge the shapes: Click and drag the Shape Builder tool across the overlapping areas of the two shapes. This will visually merge them into a single shape. If you want to remove a specific area, hold down the Alt/Option key while dragging across it with the Shape Builder Tool.

Expand Appearance: If your shapes have effects or strokes applied, you may need to expand their appearance (Object > Expand Appearance) before using the Pathfinder or Shape Builder tool for best results.
Compound Paths: If you want to create a shape with a hole in it, consider using a Compound Path (Object > Compound Path > Make). This is different from simply uniting shapes.
Experiment: The best way to learn is to experiment with different options and see what works best for your specific needs.