This article gives an overview of the different targets applied in particle accelerators and a short introduction to the material demands and the techniques established for the production. The main emphasis is placed not only on solid targets and strategies to increase their lifetime but also liquid and internal targets are touched. Special production processes for highly enriched isotopes are discussed. Finally, characterization in the sense of thickness, purity, and homogeneity is an important issue. This review is meant to be an outline, so we have provided an extensive bibliography furnishing details of the original publications.