WORLDSHEET

In string theory, the ''worldsheet'' is a two-dimensional manifold which describes the embedding of the string in spacetime. It is a direct generalization of the familiar worldline of a particle in special and general relativity.
The type of string, the geometry of the spacetime in which it propagates, and the presence of long-range background fields (such as gauge fields) are encoded in a conformal field theory defined on the worldsheet. For example, the bosonic string in 26-dimensional Minkowski space has a worldsheet conformal field theory consisting of 26 free scalar fields. Meanwhile, a superstring worldsheet theory in 10 dimensions consists of 10 free scalar fields and their fermionic superpartners.