X-ray photoelectron spectroscopy is the most important and widely used surface analysis technique. This article provides a thorough overview of X-ray spectroscopy, covering its principles, analytical methods, applica-tions, and recent progress. The principle of the technique is explained based on undergraduate-level knowledge. The crucial steps and key aspects of the analysis process are then discussed. The application section illustrates the utilization of X-ray photoelectron spectroscopy for different material categories, along with an introduction of com-monly employed techniques and their application characteristics in these domains. This article is intended to be helpful for beginners in this field, including researchers, postgraduate students, and X-ray photoelectron spectros-copy practitioners who still need to become fully acquainted with the technique, enabling them to develop a compre-hensive understanding of X-ray photoelectron spectroscopy.