The research activity of the Intense Laser Irradiation Laboratory (ILIL) is focused on fundamental studies of high-intensity laser interaction with matter and their applications. The Laboratory participates to the European Infrastructures EuPRAXIA and ELI and is part of the European consortium engaged in the laser-driven fusion research. Since 2015, the Lab is engaged in the upgrade of the laser and target area facility, in the framework of the Italian Network on Extreme Light Infrastructure (ELI-Italy), to enable laser-matter interaction studies at extreme laser intensities. Fundamental studies include plasma formation and heating by laser beams, laser-induced instabilities and other non-linear processes, atomic physics of highly-ionised plasmas, ultrashort X-ray emission and acceleration of charged particles. The Laboratory has well established collaborations with many leading international High-Power Laser Laboratories and Facilities, as well as Academic Groups. The Intense Laser Irradiation Laboratory has a long-term experience in the training of young scientists through several schemes including European Union RT Networks. In 2018, the upgrade of the infrastructure was completed in the framework of the Italian Network “Extreme Light Infrastructure” for the implementation of laser-matter interaction experiments in extreme conditions. (NEW) A further upgrade is currently under implementation within the EuAPS (EuPRAXIA Advanced Photon Sources) and IPHOQS (Integrated Infrastructure in Photonics and Quantum Sciences) projects, funded by the Next Generation Europe program (PNRR).