Reactions to nostalgia-evoking content on social media platforms like Facebook and YouTube suggest an unconscious motive of ontological security, defined as a 'sense of presence in the world as a real, alive, whole, and in a temporal sense, a continuous person'. In addition to the unprecedented access to the past provided by social media, additional factors such as increasing human longevity, the acceleration of technological and social change, the expanded size and greater interconnectedness of social networks, the proliferation of directly and vicariously experienced places and the secularisation of society have contributed to a growing need for ontological security. Engagement with nostalgia-evoking social media content fulfils the need for ontological security by reintegrating memories of the past into an ongoing, self-affirming narrative or 'life story', while the digital archiving of photos and videos offers the possibility of 'digital immortality' for a virtual self that can be projected into the future.