The Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS) is a distributed research infrastructure dedicated to high-quality observation of aerosols, clouds, and trace gases and exploration of their intricate interactions. ACTRIS delivers precision data, innovative services, and procedures regarding the 4D variability and the physical, optical and chemical properties of short-lived atmospheric constituents to improve the current capacity to analyse, understand and predict past, current and future evolution of the atmospheric environment. With a commitment to delivering high-quality and data, innovative services, and advanced procedures, ACTRIS focuses on unravelling the 4D variability and the physical, optical, and chemical properties of short-lived atmospheric constituents. By enhancing our capacity to analyse, understand and predict the past, current, and future evolution of the atmospheric environment, ACTRIS serves a diverse community of users engaged in observations, experiments, modelling, satellite data analysis, and predicting systems. At its core, ACTRIS offers access to advanced technological platforms designed to explore atmospheric processes critical for understanding air quality and climate change dynamics. Officially established as a European Research Infrastructure Consortium (ERIC) in April 2023, ACTRIS operates seamlessly across 17 European countries, coordinating and providing access to its vast array of resources and services to a wide user community. These include open access to data alongside physical and remote access to atmospheric research facilities, ensuring inclusive utilization by researchers, policymakers, and stakeholders beyond academia. Central to its operation are the integration, quality assurance, harmonization, and distribution of datasets, activities, and services, facilitated through its Central Facilities and National Facilities. The National Facilities, strategically located within Europe and at selected global sites, are tasked with acquiring high-quality data from Exploratory Platforms and Observational Platforms documenting the distribution and variability of aerosols, clouds, and trace gases. Supported by eight Central Facilities, including six Topical Centers, the Data Centre and the Head Office, ACTRIS maintains rigorous compliance with standard operating procedures and data analysis, ensuring observations of indisputable quality. The overarching mission of ACTRIS is to provide exemplary data, data products, and research facility access, nurturing innovation and furnishing dependable information to decision-makers grappling with societal challenges about air quality, climate change, and public health. Through collaborative endeavors with other research infrastructures within various project frameworks, ACTRIS contributes to the establishment of a comprehensive digital ecosystem steeped in scientific relevance. By amplifying data production, quality assurance, and accessibility, ACTRIS facilitates a deeper understanding of physical and chemical processes, effectively bridging gaps in predictive capability across local and global scales.