A modern automatic weather station (AWS) is a sophisticated collection of various components, sensors and electronics modules tied together by software, together making up a data acquisition and processing system. Many of today and tomorrow’s products follow a broadly similar set of basic processes, and this chapter sets out to explain these basic processing steps, keeping technical terminology to a minimum, and illustrating three different approaches to ‘system architecture’. The oversight provided by this chapter provides familiarity with the key concepts, system approaches and application types, and from there users can review potential products and suppliers using Internet search facilities to gather up-to-date product information.