  Superconductivity has been discovered recently in nickel based 112 infinite
thin films $R_{1-x}$A$_x$NiO$_2$ ($R$ = La, Nd, Pr and A = Sr, Ca). They are
isostructural to the infinite-layer cuprate (Ca,Sr)CuO$_2$ and are supposed to
have a formal Ni 3$d^9$ valence, thus providing a new platform to study the
unconventional pairing mechanism of high-temperature superconductors. This
important discovery immediately triggers a huge amount of innovative scientific
curiosity in the field. In this paper, we try to give an overview of the recent
research progress on the newly found superconducting nickelate systems, both
from experimental and theoretical aspects. We will focus mainly on the
electronic structures, magnetic excitations, phase diagrams, superconducting
gaps and finally make some open discussions for possible pairing symmetries in
Ni based 112 systems.
