This paper describes the latest version of algorithm MAIAC used for processing of the MODIS Collection 6 data record. Since initial publication in 2011–2012, MAIAC has changed considerably to adapt global processing and improve cloud/snow detection, aerosol retrievals and atmospheric correction of MODIS data. The main changes include 1) transition from 25 km to 1 km scale for retrieval of the spectral regression coefficient (SRC) which helped remove occasional blockiness at 25 km scale in the aerosol optical depth (AOD) and in the surface reflectance; 2) continuous improvements of cloud detection; 3) introduction of “Smoke” and “Dust” tests to discriminate absorbing fine and coarse mode aerosols; 4) adding over-water processing; 5) general optimization of the LUT-based radiative transfer for the global processing, and others. MAIAC provides an inter-disciplinary suite of atmospheric and land products, including: cloud mask (CM), column water vapor (CWV), AOD at 0.47 and 0.55 μm, aerosol type (background/smoke/dust), and fine mode fraction over water; spectral bidirectional reflectance factors (BRF), parameters of Ross-Thick Li-Sparse (RTLS) BRDF model and instantaneous albedo; for snow-covered surfaces, we provide sub-pixel snow fraction and snow grain size. All products come in standard HDF4 format at 1 km resolution, except BRF which is also provided at 500 m resolution, on Sinusoidal grid adopted by the MODIS land team. All products are provided on per-observation basis in daily files except BRDF/albedo which is reported every 8 days. Because MAIAC uses a time series approach, the BRDF/albedo are naturally gap-filled over land where missing values are filled-in with results from the previous retrieval. While the BRDF model is reported for MODIS land bands 1–7 and ocean band 8, BRF is reported for both land and ocean bands 1–12. This paper focuses on MAIAC cloud detection, aerosol retrievals and atmospheric correction and describes MCD19 data products and quality assurance (QA) flags.