Worldsheet
String theory 

Fundamental objects 
Perturbative theory 
Nonperturbative results 
Phenomenology 
Mathematics 
Theorists

In string theory, a worldsheet is a twodimensional manifold which describes the embedding of a string in spacetime.^{[1]} The term was coined by Leonard Susskind around 1967 as a direct generalization of the world line concept for a point particle in special and general relativity.
The type of string, the geometry of the spacetime in which it propagates, and the presence of longrange background fields (such as gauge fields) are encoded in a conformal field theory defined on the worldsheet. For example, the bosonic string in 26dimensional 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.
References
 ↑ Di Francesco, Philippe; Mathieu, Pierre; Sénéchal, David (1997). Conformal Field Theory. p. 8. doi:10.1007/9781461222569. ISBN 9781461222569.