In layering, a branch of stem of a plant is bent downwards facing the soil in such a away that half of the branch gets buried in the soil while the tip remains exposed outside the soil. The half covered in soil evolves into roots. After separating from the mother plant, this part of the branch starts to grow freely into a new and independent daughter plant.
Example: brambles, sphagnum moss and lemon.
In plants like strawberry and raspberry, this process can occur automatically. This is because sometimes the branch might get buried in the soil naturally. This again results in a daughter plant.