(related to Definition: Subspace)
Please note that every vector space V over a given field F has two trivial subspaces:
U is sometimes also called the zero space. The vector 0_V has to exist, since (V,\oplus) is a group, which is part of the definition of vector space. The index of the vector 0_V is used to differentiate it from the zero element of the addition 0\in F, and can be omitted, if it is clear from the context, which zero element is meant.