This digital resource is a comprehensive collection of immunohistochemistry (IHC) protocols and a troubleshooting guide provided by Abcam, a leading supplier of antibodies and reagents. IHC is a widely used technique in biology and medicine for visualizing specific antigens in tissue sections using antibodies. This resource aims to assist researchers in successfully performing IHC experiments and resolving common issues. The protocols cover various aspects of IHC, including sample preparation (fixation, embedding, sectioning for paraffin-embedded and frozen samples), antigen retrieval methods (heat-mediated and enzymatic), blocking steps, antibody incubation (primary and secondary), and detection systems (chromogenic and fluorescent). It provides step-by-step guidelines to ensure robust, reliable, and reproducible results. The troubleshooting guide addresses common problems encountered during IHC, such as no staining, high background, or non-specific staining. It offers potential causes for these issues and provides expert solutions and tips to rectify them, including optimizing antibody concentrations, improving tissue preparation, and selecting appropriate controls. This resource is essential for researchers in pathology, neuroscience, oncology, and other fields utilizing IHC for protein localization and expression analysis. It helps both beginners and experienced users to optimize their IHC workflows, ensuring high-quality data for their research. Abcam's reputation for antibody validation further enhances the reliability of the protocols and advice provided.