Shoots are new growth, they are very young branches that have not hardened yet.
If shoots are not dealt with regularly they take over the tree and make it lose its shape very rapidly.

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Some shoot pruning guidelines:
- as with branches these are best pruned aggressively when the tree is growing vigorously in spring or early summer.
- they can however be dealt with all year round in small quantities
- don't prune shoots if the tree is in flower.
- also cut just above a bud.
- use very sharp instruments (pruning scissors preferably)
- leave shoots sufficient growth time to thicken
- trim shoots with 6 - 8 pairs of leaves, leave 2- 3 behind
- more aggressively pruned shoots produce thicker shoots and ultimately a better bonsai.