Increased use in recent years of social networking applications such as Facebook has resulted in a rapid growth of user generated content. As a communication tool for social engagement, the online patterns and characteristics of individuals and user types can now be better understood by monitoring user behaviour, activity frequency and modality of use. The aim of this paper is to present an analysis of the behaviour and characteristics of young and older user groups in an online social network. Our findings show that correlations exist between user behaviour and age, based upon activities as evidenced within the data. Visualisation of full user activity has further helped our understanding of user behaviour by identifying interaction patterns, which may be used for the monitoring of social engagement.