  Record Dynamics (RD) deals with complex systems evolving through a sequence
of metastable stages. These are macroscopically distinguishable and appear
stationary, except for the sudden and rapid changes, called quakes, which
induce the transitions from one stage to the next. This phenomenology is well
known in physics as "physical aging", but from the vantage point of RD the
evolution of a class of systems of physical, biological and cultural origin is
rooted in a hierarchically structured configuration space and can therefore be
analyzed by similar statistical tools. This colloquium paper strives to present
in a coherent fashion methods and ideas that have gradually evolved over time.
To this end, it first describes the differences and similarities between RD and
two widespread paradigms of complex dynamics, Self Organized Criticality and
Continuous Time Random Walks. It then outlines the Poissonian nature of records
events in white noise time series, and connects it to the statistics of quakes
in metastable hierarchical systems, arguing that the relaxation effects of
quakes can generally be described by power laws unrelated to criticality.
Several different applications of RD have been developed over the years. Some
of these are described, showinghe basic RD hypothesis, the log time homogeneity
of quake dynamics, can be empirically verified in a given context. The
discussion summarizes the paper and briefly mentions applications not discussed
in detail. Finally, the outlook points to possible improvements and to new
areas of research where RG could be of use.
