Basic Drawing - Shading and Value

Value is the degree of lightness or darkness in a colour. 
Tint- White
Tone - Gray
Shade - Black

Shading terms.
-Highlights: small areas of white used to show the brightest spots of an object.
-Midtones: used to show the actual colour of the object.
-Core of the shadows: represents the shadowed side of the object.
-Reflected light: a faint rim of light reflected back onto an object from the surfaces surrounding the object,
-Cast shadow: the shadow where the object meets the surface (the darkest tones)

Shading techniques.
-Hatching: a row of lines, all facing in the same direction. More dense and concentrated in the darker areas.
-Cross hatching: similiar to hatching, but with the addition pf criss-cross lines.
-Contour hatching: follows the contour, or curve, or outline, of the object. The hatching must match the shape of the object.
-Scribbling: tiny, aquiggly lines. It can be controlled, and it's called controlled scribbling. It has other names such as scumbling, circling and squirkling. This technique basically uses random strokes to create shading.
-Dots or Stippling: placing a lot of dots on paper to indicate shading. The most time-consuming of all shading techniques, but it creates some neat effects.
-Blending: also known as smooth shading. You can use your finger, or a smudge tool such as a piece of cloth, or cotton swab, etc, to smear the shading to create a more uniform shade. If controlled and done correctly, this can give a smooth polished look to the shading.