In this master class, I will introduce spatial transcriptomics and then focus on their pre-processing. In particular, I will present our recent work on evaluating computational methods for detecting spatially variable genes (SVGs) in spatial transcriptomics data analysis. The identification of genes that vary across spatial domains in tissues and cells is an essential step for spatial transcriptomics data analysis. Given the critical role it serves for downstream data interpretations, various methods for detecting SVGs have been proposed. Our study systematically compares these approaches from multiple perspectives, offering insights into choosing methods.