How did democracy, a regime of a numerically insignificant minority in Antiquity, evolve to a 21st century self-evidence in (and beyond) the Western world? Given the spring of democracy in the Muslim world, the youth movement for greater factual equality in some Western countries and the substitution of some communist regimes by severe capitalism, the factual world can make use of this reference work. It reports on today's thinking on the long evolution of democracy as a political regime, its setbacks and its directions. Robert Senelle is Professor Emeritus of Public and Comparative Law at the University of Ghent (Belgium). Emile Clement is Honorary Director of the Chamber of Representatives of the Belgian Parliament. Edgard Van de Velde was associate professor constitutional, comparative and European law at EHSAL-Brussels (Belgium) from 1985 until 2008."