In mathematics, the Zariski topology is a structure basic to algebraic geometry, especially since 1950. It is named after its originator, Oscar Zariski.

The Zariski topology is defined by defining the closed sets to be the sets consisting of the mutual zeroes of a set of polynomials. (See affine varieties)

This is a topology, because two basic axioms can be checked. The intersection of any number of closed sets is the set of mutual zeros of the union of all the defining polynomials. The union of two closed sets, defined by polynomials P_i and Q_j, is the set of mutual zeros of the set of products P_iQ_j.

Remarks

This definition indicates the kind of space that can be given a Zariski topology: for example, we define the Zariski topology on an n-dimensional vector space Fⁿ over a field F, using the definition above. That this definition yields a true topology is easily verified.

Using the Noetherian property of the ring of polynomials over F, one sees that any closed set is the set of zeroes of a finite set of equations.

The Zariski topology given to some finite-dimensional vector space doesn't depend on the specific basis chosen; for that reason it is an intrinsic structure. It is usually regarded as belonging to the underlying affine space, since it is also invariant by translations.

One can generalise the definition of Zariski topology to projective spaces, and so to any algebraic variety as subsets of these. The general case of the Zariski topology is based on the affine scheme and spectrum of a ring constructions, as local models.