Fig. 1 Select a path
Fig. 2 Click a brush on the Brushes palette.
Fig. 3 A calligraphic brushstroke is applied.
Fig. 4 An art brushstroke.
Fig. 5 A scatter brushstroke.
Fig. 6 Another scatter brushstroke (made from five birds).
Fig. 7 A pattern brushstroke.
Choose Window menu > Show Brushes, if the palette is not already displayed.
Click a brush on the brushes palette, then drag the selected brush onto an existing path (the path need not be selected first). Release the mouse when the hand pointer is directly over the edge of the object.
Select a path of any kind (except a type path) (Figure 1), then click a brush on the Brushes palette (Figures 2-7).
You can't apply a brushstroke to a type path, but you can convert type into outlines and then apply a brushstroke to the outlines.
For a scatter brush, you have the option, via the Brush Options dialog, to make the size, spacing, scatter, and rotation variables more or less random.