  The aim of this review-style paper is to provide a concise, self-contained
and unified presentation of the construction and main properties of Gaussian
multiplicative chaos (GMC) measures for log-correlated fields in 2D in the
subcritical regime. By considering the case of the 2D Gaussian free field, we
review convergence, uniqueness and characterisations of the measures; revisit
Kahane's convexity inequalities and existence and scaling of moments; discuss
the measurability of the underlying field with respect to the GMC measure and
present a KPZ relation for scaling exponents.
