Make or release a compound path
A compound path is just when you combine multiple individual paths into one single path. Shapes must be converted to paths before being included in a compound path. For more information, see Convert a shape to a path.
Select two or more paths you want to turn into a compound path. (To select multiple objects, hold the CTRL key.)
On the Object menu, point to Path, and click Make Compound Path.
The resulting path will replace the bottom-most path (in Z-order) that was selected before compounding, adopting that path's properties.