Systems biology adopting integrative omics approaches aims to understand the biology of complex diseases in a holistic framework. Rapid development of omics techniques like genomics, transcriptomics, proteomics, metabolomics, lipidomics and so on, along with computational/bioinformatics methods and tools is advancing our understanding of biological systems in exquisite molecular details. Multi-omics and integrative approaches are increasingly being used to study biological systems in health and to unearth hitherto unknown molecular players in many complex genetic diseases including: human microbiome .infection and immunological diseases, host-pathogen interactions, as well as metabolic disorders like diabetes and cardiovascular diseases. Combining the power of the so-called “hypothesis-free” omics methods and “hypothesis-driven” molecular biology methods can synergistically push the frontiers of biological knowledge in these research areas.