The Observer is the professional software package for the collection, analysis and presentation of observational data. Providing a wide range of features for data collection and analysis, The Observer can be applied to study observable behavior such as activities, postures, gestures, facial expressions, movements, and social or human-system interactions. The Observer comes in different modules to suit different research requirements and can be integrated with data acquisition systems and/or extended with a number of accessories to support the collection of observational data.