a central sequence in a $c^*$-algebra is a sequence (x\_n) of elements such that [x\_n, a] converges to zero, for any element a of the $c^*$-algebra. in von neumann algebra setting one typically means the convergence with respect to tracial norms, while in $c^*$-theory it is with respect to the $c^*$-norm. in this talk we will consider the $c^*$-theory version of central sequences. we will discuss properties of central sequence algebras and in particular address a question of j. phillips and of ando and kirchberg of which separable $c^*$-algebras have abelian central sequence algebras. \\ \\ joint work with dominic enders.