  Soft materials often exhibit a distinctive power-law viscoelastic response
arising from broad distribution of time-scales present in their complex
internal structure. A promising tool to accurately describe the rheological
behaviour of soft materials is fractional calculus. However, its use in the
scientific community remains limited due to the unusual notation and
non-trivial properties of fractional operators. This review aims to provide a
clear and accessible description of fractional viscoelastic models for a broad
audience, and to demonstrate the ability of these models to deliver a unified
approach for the characterisation of power-law materials. The use of a
consistent framework for the analysis of rheological data would help classify
the empirical behaviours of soft and biological materials, and better
understand their response.
