Author’s abstract: Minimal surfaces in Euclidean 3-space, i.e. conformal harmonic maps, enjoy two important properties: They allow a circle of isometric deformations rotating the principal curvature directions, the so called associated family, and they are obtained as the real part of holomorphic functions into \(\mathbb C^3\). These properties are shared by arbitrary (pluri-)harmonic maps into Euclidean \(n\)-space. Replacing \(\mathbb R^n\) by an arbitrary symmetric space leads to similar results, but the role of \(\mathbb C^n\) is played by an infinite dimensional complex homogeneous space acted on by a twisted loop group. We give a survey of the development of this theory from our view point, and we discuss applications to the construction of (pluri-)harmonic maps into symmetric spaces and their rank restrictions.