Since the advent of single-cell sequencing technology in 2009, it has undergone over a decade of development and optimization (Figure 2b). Various single-cell isolation and sequencing techniques for different omics have also been developed (Figure 2a). Among these, the most mature and widely used technology is single-cell transcriptome sequencing (single-cell RNA-seq, scRNA-seq). By 2015, scRNA-seq technology had achieved ultra-high throughput levels, capable of sequencing thousands of cells in a single run on a droplet microfluidics platform (3’scRNA-seq), enabling rapid sequencing of a large number of cells.