Graphite is probably the most common drawing medium that there is. Graphite most commonly comes in the form of a pencil and is what most of us simply refer to as "pencil". Therefore, a lot of graphite drawings are simply called pencil drawings, even though calling them graphite drawings would be more accurate.
Hatching and Cross Hatching:
The first two graphite drawing techniques is called "hatching and crosshatching". These techniques can be used with a variety of drawing media besides graphite. Hatching and crosshatching is achieved by drawing lines to create value. These lines may cross over each other. The more the lines cross over each other, the darker the value. By varying the frequency of marks, a range of value can be achieved. This range of value leads to the illusion of form.
Hatching is the process of drawing lines that do not cross over each other. The closer that these lines are placed to each other, the darker the value. This assumes that you're working on white paper with a dark drawing medium. In the apple drawings pictured below, you'll notice that the lines curve slightly around the form. Since the directional strokes that we make can influence the illusion of form, we should be mindful of the direction of the stroke.
Like hatching, cross hatching relies on the concentration of lines to produce the required value. With cross hatching, the lines do cross over each other. This allows the artist a bit more flexibility. But like with hatching, we should consider the form of the subject when applying the lines. The lines should flow over the form of the subject. Notice in the image below how the lines are curved slightly as they flow over the form of the apple.
If speed is what you're after, then using random or squiggly lines may be the technique that you choose. Value is achieved with this method by applying random lines. Just like with hatching and crosshatching, the frequency of crossing lines affects the values created. This technique is great for quick sketching and for creating interesting textures.
Stippling is the process of applying countless dots to develop the value. The closer that the dots are placed to each other, the darker the value. Stippling is most commonly used with pen and ink, although it can also be used with other drawing and painting media. If used in a pencil drawing, it's advised to use a softer and darker graphite pencil so that the dots are dark enough to be visible.Stippling provides a high level of control over the value produced.