  This article briefly reviews recent theoretical developments in quantum
critical phenomena in one-dimensional (1D) integrable quantum gases of cold
atoms. We present a discussion on quantum phase transitions, universal
thermodynamics, scaling functions and correlations for a few prototypical
exactly solved models, such as the Lieb-Liniger Bose gas, the spin-1 Bose gas
with antiferromagnetic spin-spin interaction, the two-component interacting
Fermi gas as well as spin-3/2 Fermi gases. We demonstrate that their
corresponding Bethe ansatz solutions provide a precise way to understand
quantum many-body physics, such as quantum criticality, Luttinger liquids, the
Wilson ratio, Tan's Contact, etc. These theoretical developments give rise to a
physical perspective using integrability for uncovering experimentally testable
phenomena in systems of interacting bosonic and fermonic ultracold atoms
confined to 1D.
