Z39.50 and (to a slightly lesser extent) SR, seem to be difficult terms to escape these days in the library world. They have of course been discussed in the library IT world for some years. It is likely that by now most members of the profession will at least have heard of the existence of Z39.50/SR, even if they do not understand its technical detail, which is usually unnecessary in any case. It is the intention of this overview to offer some background information and explanation for those still wondering what the fuss is all about; highlight some current issues with implications for libraries; and finally provide a report on what stage the library system suppliers have reached in their efforts to keep up with (or lead?) developments and implement Z39.50/SR.