Wherever there are workers, there are unions: and we need them now, more than ever.

Whether in formal organisations or grass-roots collectives, people have always found ways to work together for a better world. Today, a historic wave of strikes and union organizing is sweeping the globe - from teachers to Amazon workers, barristers to actors, train-drivers and doctors alike. Dealing with an unprecedented cost-of-living crisis, rising inequality, and rule by some of the richest leaders in history, ordinary people have had enough. And yet many of us have lost the central source of our political power: the union.

Union is the first global philosophy and history of trade unions, which shows how the health of our democracies is the health of our unions. Tracing the idea of unions from the ancient world up through the present - from ancient Rome and the historic struggles for workers' rights in Europe, to the fights for decolonization and against authoritarian regimes in the Global South - and drawing on political theory, social science and current affairs, it challenges our narrow idea of unions to show how they are crucial, not just to achieve better conditions for their members, but a healthier state of democracy for all of us.

Union shows us that, if we are to save democracy today, we need a new vision: one that puts the organized power of ordinary citizens at the heart of its rebirth.