Recently, several ‘omics’ technologies enable quantitative measuring of the abundance of various biological entities in a large-scale, and thus allow comparison of their variation between different physiological states on a genomic scale. No single ‘omics’ analysis can fully reveal the complexities of fundamental biology, and thus integration of multiple layers of information, the multi-‘omics’ approach, is required to acquire a precise picture. Bioinformatics has essential roles in the analyses of all areas of omics studies. Today, I’d like to introduce two different aspects of our studies: (1) a study related to understanding underlying alterations associated with human diseases and (2) a study related to genome evolution. Specifically, one of which is to introduce a study basically based on the analysis of RNA-seq data derived from lean and obese adipose tissues in humans, to reveal how lean and obese adipogenesis differ in terms of gene expression. Another is to introduce a study exploring the properties of first introns in the human genome, showing that first introns are unique in the degree of evolutionary conservation and the existence of various functional signatures. I hope my talk will help the students to get an idea of how bioinformatics can help approach complex biological questions using various types of omics data.