Sousveillance, from the French words sous (below) and veiller (watch), means “to watch from below.” Conceptually, it is positioned as a resistive force that challenges surveillance societies. A nuanced term sousveillance must be discussed both as a technology and as a social practice, and the various ways its conceptualization has changed as technologies and social practices have evolved. As sousveillance has moved from the avant-garde to the mainstream since the mid-1980s, it is helpful to reflect on the relationship between ubiquitous sousveillance and ubiquitous surveillance—a condition that our society is fast approaching— and to consider the implications for sousveillance’s contemporary resistive potential. This entry discusses the origin of the term, 'sousveillance'; different definitions of sousveillance; its mainstreaming; moving beyond the visual metaphor; and the move towards ubiquitous sousveillance and surveillance.