The renormalisation group framework was at the origin of great success in the domain of high energy physics. Hereafter, I present new domains in which RG is used to improve our comprehension of nature. First, we use it to reimagine the Grand Unification interpretation as an asymptotic process instead of a discrete view. This permits to get rid of the proton decay and to introduce new particles and particularly a dark matter candidate. In a second time, RG is used to model the evolution of the Covid-19 pandemics that was raging in 2020, from multiple wave pattern to social distancing measures and inter-countries interaction modelisation, showing the wide utilisation of this mathematical toolkit to describe Nature.