This paper is devoted to general properties of the central configurations: we do not make any restriction on the number n 3 of particles nor on the dimension d 1 of the configuration. Part 7 considers however the particular case n = d + 2, of interest because the case n = 4, d = 2 is the first for which we cannot solve the equations for central configurations. Our main result is Proposition 6, which gives some estimates implying an important estimate due to Our main tool is Equation (4.5).