Endodontically treated teeth (ETT) with significant tissue loss commonly require intraradicular post systems to support the coronal restoration and restore function and esthetics. These posts, which are placed within the root canal, have been manufactured from various materials and in different designs throughout history. Today, fiber posts are favored because of their physical properties similar to dentin, esthetic advantages, ease of use, and compatibility with adhesive techniques. This review aims to evaluate the general characteristics of currently used fiber post systems for the restoration of ETT, examine clinically observed failures and their causes, and discuss application principles alongside recent clinical studies.