The paper reports the experimental discovery of a Weyl semimetal in TaAs, a noncentrosymmetric and nonmagnetic material. The authors used angle-resolved photoemission spectroscopy (ARPES) to observe Fermi arcs on the (001) surface of TaAs, which are characteristic of Weyl semimetals. First-principles calculations confirmed the presence of Weyl nodes and the Fermi arcs, validating the experimental findings. The study provides strong evidence for the existence of Weyl semimetals and highlights their unique properties, such as chiral anomalies and magnetic monopoles in crystal momentum space. The work also discusses the differences between Fermi arcs in Weyl semimetals and Dirac semimetals, emphasizing the topological nature of Weyl semimetals.The paper reports the experimental discovery of a Weyl semimetal in TaAs, a noncentrosymmetric and nonmagnetic material. The authors used angle-resolved photoemission spectroscopy (ARPES) to observe Fermi arcs on the (001) surface of TaAs, which are characteristic of Weyl semimetals. First-principles calculations confirmed the presence of Weyl nodes and the Fermi arcs, validating the experimental findings. The study provides strong evidence for the existence of Weyl semimetals and highlights their unique properties, such as chiral anomalies and magnetic monopoles in crystal momentum space. The work also discusses the differences between Fermi arcs in Weyl semimetals and Dirac semimetals, emphasizing the topological nature of Weyl semimetals.