Erosive gastritis still represents a significant health problem, increasing in prevalence in the last few years. Due to its burden on health and the economy, there is a need for novel biomarkers to understand its molecular pathology and develop new treatments. Immunohistochemistry has emerged as a valuable tool in gastritis research, enabling the visualization and analysis of specific proteins within tissue sections. This review aims to provide a comprehensive overview of the application of immunohistochemistry in gastritis research, highlighting its contributions to revealing the complex molecular mechanisms involved in the progression of gastritis. The applications gained from these studies hold promise for developing targeted therapies and improving patient outcomes in managing erosive gastritis. Several molecules have been identified and tested in recent years for their clinical relevance in research. In this paper, we will focus on the well-known markers. Furthermore, this review emphasizes diagrammatic illustrations visually representing the molecular interactions underlying pathogenesis. These illustrations enhance the clarity and understanding of the reviewed concepts.