The word literally means "tray planting", and is a Japanese term of art for horticultural techniques for producing small trees in containers that mimic the shape of full sized trees. Bonsai is a Japanese continuation of the Chinese art of penjing.
Bonsai can come from propagation, nursery stock, or wild collection(yamadori) like the common elm in the photo.
Nursery stock and collected material are often heavily pruned and reshaped, as depicted.
Trees planted in shallow trays require special care such as leaf trimming, pruning, repotting, root pruning, wiring, defoliation, and "dead wood" (jin).
Repotting shown in this album, allows roots to be trimmed, the tree to be repositioned, and allows future growth to be planned.
2" semi cascade larch
Traditional upright wych elm
Semi cascade with shari and jin
one of my trees