This report provides a comprehensive analysis of consumer behaviour and decision-making processes, specifically focusing on the online retailer ASOS plc. It begins by outlining the five stages of the consumer decision-making journey: need recognition, information search, evaluation of alternatives, purchasing decision, and post-purchase behaviour, illustrating how these stages apply to ASOS's target market. The report then emphasizes the importance for marketers to map and understand this journey, highlighting the value of customer journey mapping in understanding customer interactions and optimizing customer experiences. It also contrasts the decision-making processes in Business-to-Consumer (B2C) and Business-to-Business (B2B) contexts, discussing the differing marketing tactics and promotional strategies employed in each. Furthermore, the report explores different market research approaches suitable for both B2C and B2B environments, including lean market research and surveys. Overall, the report offers insights into how ASOS can enhance its marketing strategies by understanding and adapting to consumer behaviour.