Set of vectors in that:

  1. Spans the vector space: Every vector in can be expressed as a linear combination of basis vectors.
  2. Is linearly independent: No vector in the basis can be written as a linear combination of other basis vectors.

For Matrix = Independent columns that fill Column Space

Intuition

A basis allows each element of to be uniquely represented by a combination of basis vectors. In finite-dimensional spaces, the basis gives a minimal set of “building blocks” for the space. In infinite-dimensional spaces, a basis may consist of infinitely many vectors but still enables unique representation.