Abstract: It is generally believed that a system of partons (gluons) at high energy (or small Bjorken-x) forms a new state of matter, the so-called Color-Glass-Condensate where the gluon distribution saturates and non-linear coherence phenomena dominate. Such a state of matter is universal and many small-x phenomena including the observed geometric scaling at HERA, RHIC and the LHC, Ridge, dihadron decorrelation, shadowing, suppression of particle production at forward rapidities can be uniquely described within this approach. I review the topics and present recent indications of gluon saturation at the LHC in p+p and p+A collisions. In particular, I will discuss that the upcoming proton-lead (p+Pb) collisions at the LHC will provide crucial benchmarks for understanding the characteristic of Quark-Gluon-Plasma produced in heavy ion collisions at the LHC and RHIC.