The Visium Spatial Gene Expression solution by 10X Genomics enables spatial profiling of gene expression in intact tissue sections, preserving cellular spatial context. For fresh-frozen tissues, the protocol involves sectioning, mounting, fixation, permeabilization, reverse transcription, library preparation, sequencing, and spatial mapping. For FFPE tissues, additional steps include deparaffinization, rehydration, antigen retrieval, and tissue mounting with Visium Cytassist. Both protocols end with library preparation, sequencing, data analysis, and spatial mapping to retain spatial information.