Lithosphere, in simpler words, is crustal rock and mantle rock down to a zone in the mantle that is lubricious enough to allow the plates to move. Thumbs tucked, fingers flat, the hands side by side, press them hard together until they buckle upward. The hands are two continents, or other landmasses, converging, colliding-making mountains. The Himalaya was made that way.
Place the hands flat again, slowly move them apart. These are two plates separating, one on either side of a spreading center. The Atlantic Ocean was made that way. Slide one hand under the other. This is subduction. Ocean floors are consumed that way. Thumbs tucked, fingers flat, palms again side by side, slide one hand forward, one back, the index fingers rubbing. This is the motion of a transform fault, a strike-slip fault- the San Andreas Fault.
-Assembling California, by John McPhee