During the past years, nanophotonics has provided new approaches to study the biological processes below the optical diVraction limit. How single molecules diVuse, bind and assemble can be studied now at the nanometric level, not only in solutions but also in complex and crowded environments such as in live cells. In this context Xuorescence Xuctuations spectroscopy is a unique tool since it has proven to be easy to use in combination with nanostructures, which are able to conWne light in nanometric volumes. We review here recent advances in Xuorescence Xuctuations' analysis below the optical diVraction limit with a special focus on nanoapertures milled in metallic Wlms. We discuss applications in the Weld of single-molecule detection, DNA sequencing and membrane organization, and underscore some potential perspectives of this new emerging technology.