From the public space, in the singular, which designates the sphere of the political debate, the publicity of the private opinions, to the public spaces which, since the 1980s in France, correspond to all the traffic lanes open to the public, in the metropolises and in the urbanized villages, a remarkable synthesis on these spaces of "communication", at the crossroads of the urban, the political, the philosophy. In the singular, public space refers to the sphere of political debate, the publicity of private opinions. In the plural, the public spaces correspond to the road network, streets and boulevards, squares and forecourt, parks and gardens, in short to all the traffic lanes open to the public, in the metropolises as in the urbanized villages. Both are part of the communication. Globalization, the communication revolution, video surveillance, the multiplication of real and virtual walls "erase" public spaces. Global urbanization (shopping centers, mass tourism, street furniture, secure enclaves, etc.) is transforming their uses and standardizing them. However, resistances manifest themselves (street art, street shows, street code, cyber-street, feminist actions, etc.) that combine public spaces, free and accessible, the three qualities of cities: urbanity, diversity and otherness.