The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) studies properties and phase transitions of nuclear matter in various nucleus-nucleus collisions at center-of-mass energies per nucleon collision root s(NN) = 7.7-200 GeV. With a fixed target made of gold foils installed inside the beam pipe, STAR also starts to explore high baryon density regime (mu(B) approximate to 420-720 MeV) at root s(NN) = 3.0-7.7 GeV. A few selected results reported by the STAR collaboration at the Quark Matter 2018 (QM2018) conference are described in these proceedings.