Purpose: The purpose of this paper is to provide a perspective on the emergence of social media and their adoption as a critical element in knowledge management strategy. Social media are defined as the collection of software tools and web-based applications that are personalized, that is, that communications identify individuals by name and enable the development of human relationships. Specific tools and software applications include blogging, wikis, microblogging, social networking services, tagging, subscribing, and so on. Design/methodology/approach: The paper uses 1999 as a pivotal year, describing how research in social network theory preceded and then co-evolved with the development of applications during the dot.com boom and coincided with the emergence of a third phase in knowledge management, a phase in which the emphasis has been on enabling social networks as a primary focus for KM work. Findings: The paper presents a model for understanding how social media have augmented communication and collaboration methods and have introduced new dimensions in work practices, namely, peripheral awareness, crowd sourcing, and network maintenance. Practical implications: The paper puts forward a potential guide in helping practitioners to make sense of the plethora of social tools, social networking sites, and web applications, and to make better decisions about which tools to apply depending on specific circumstances and learning and knowledge management goals. Originality/value: The paper reflects the personal experience and practice of the author, who has worked in the field of knowledge management, collaboration, and networks, for over 20 years.