Cross hatching is a used by artists to add dimension and shadows to their art. The artistic technique used to add shadow and dimension to drawn objects. It involves filling a space with at least two sets of lines, with the second set crossing over the first to create a darker effect. You can use parallel lines to fill an area with tone. By varying the spacing and width (pressure) of the lines you can make areas darker or lighter.
If it takes multiple strokes to make a longer line, try leaving smaller irregular spaced gaps between one line and the next. If you overlap the strokes often you will make irregular blotches Irregular spaced gaps add a a different dimension to your technique.
Scribble Hatching is using various lines to fill in the gaps moving your writing tool in different movements (up, down, vertical, horizontally). You can overlap circles or squiggles. This creates a rough, loose texture. To darken, add more squiggles over the squiggles. Blur your eyes to find areas of uneven value and fill these with additional marks.
Ink artists use cross hatching often in their art. You will also see it used in architectural designs.