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 sNN=7.7-200GeV. With a fixed target made of gold foils installed inside the beam pipe, STAR also starts to explore high baryon density regime (μB≈420-720MeV) at sNN=3.0-7.7GeV. A few selected results reported by the STAR collaboration at the Quark Matter 2018 (QM2018) conference are described in these proceedings.