Semantic image segmentation (SiS) plays a fundamental role towards a general understanding of the image content and context, in a broad variety of computer vision applications, thus providing key information for the global understanding of an image. This monograph summarizes two decades of research in the field of SiS, where a literature review of solutions starting from early historical methods is proposed, followed by an overview of more recent deep learning methods, including the latest trend of using transformers. The publication is complemented by presenting particular cases of the...