The fastest supercomputer in Europe and one of the fastest in the world has been operational since 2021. Its computational power exceeds 550 PFLOPS (which can be compared to the power of 1.5 million modern laptops) and has 117 PB of disk resources. The preexascale LUMI, which stands for The Large Unified Modern Infrastructure, was established in Kajaani, Finland, as part of the EuroHPC Joint Undertaking (EuroHPC JU). The LUMI consortium, which includes Finland, Poland, Belgium, Czech Republic, Denmark, Estonia, Iceland, Norway, Sweden and Switzerland, was responsible for its construction. In addition to its enormous computing power, LUMI is equipped with specialised partitions and scientific software packages, allowing it to perform significantly more calculations in an even shorter time and with much greater precision than before. This opens up new, previously inaccessible possibilities for scientists, offering opportunities for faster technological and economic development. Polish scientists and entrepreneurs can access LUMI resources through the National Competence Centre in HPC.