Linked from
The 11 pages that link to Lie bracket, each with the reason it gives.
Affine connectionRelated: The bracket appears in the connection's defining torsion expression.
Sophus LieBroader topic: Brackets capture how the infinitesimal transformations combine.
Jacobi identityRelated: The identity specifies how this operation must combine nested brackets.
Adjoint representationRelated: The derivative of the adjoint action gives the bracket operation.