Lignocellulosic biomass is the most abundant, ubiquitous polymer on Earth available to benefit mankind. Biomass biorefinery has taken center stage in the world’s economy and is becoming diverse with time. With biorefinery, cascades of products can be obtained from biomass rather than a single product. It is a complex structure that consists of three polymers as cellulose, hemicellulose and lignin, linked to each other in a compact intricate manner making it difficult to be attacked by microorganisms. Still, many microorganisms have evolved strategies to consume this abundant material as an energy source. Degradation of lignocellulosic biomass is not only a survival strategy for these microbes, but its destruction also plays a pivotal role in carbon recycling of Earth through the fixation of photosynthetically fixed carbon present in plant biomass. Mankind has explored the capacity of microorganisms to produce polymer-degrading enzymes to deconstruct its basic components. Biomass-degrading enzymes have attracted researchers worldwide as this is the most sustainable way to obtain fermentable sugars from this most abundant biomass. Synergism among enzymes as well as their various components are presented along with challenges of biomass hydrolysis and probable solutions. © 2024 selection and editorial matter, Reeta Rani Singhania, Anil Kumar Patel, Héctor A. Ruiz, Ashok Pandey; individual chapters, the contributors.