  Recent theoretical and observational findings breathed new life into the
field of RR Lyrae stars. The ever more precise and complete measurements of the
space asteroseismology missions revealed new details, such as the period
doubling and the presence of the additional modes in the stars. Theoretical
work also flourished: period doubling was explained and an additional mode has
been detected in hydrodynamic models as well. Although the most intriguing
mystery, the Blazhko-effect has remained unsolved, new findings indicate that
the convective cycle model can be effectively ruled out for short- and
medium-period modulations. On the other hand, the plausibility of the radial
resonance model is increasing, as more and more resonances are detected both in
models and stars.
