QA4EO-2 activities are related to the research and development of new ideas or improvement of existing ones important to the evolution of algorithms and calibration and validation processes of ESA EO products. QA4EO-2 also includes activities related to the development of expertise in metrology, particularly in the derivation and the expression of uncertainties. Progress towards incorporating metrological information in EO data products is important to support the communication of data quality and fitness for purpose to users. Also included within QA4EO-2 are the activities related to the research and development of innovative methodologies for assessing the quality of EO products, from various data providers, to increase the confidence in data quality and in fitness for purpose.