This paper reports the experimental discovery of Weyl semimetal TaAs through angle-resolved photoemission spectroscopy (ARPES). The researchers observed Fermi arcs on the surface of TaAs, which are a hallmark of Weyl semimetals. These arcs connect projections of Weyl nodes with opposite chirality on the surface. First-principles calculations confirmed that TaAs is a Weyl semimetal, with a dozen pairs of Weyl nodes in the Brillouin zone. The absence of inversion symmetry in TaAs's crystal structure leads to the emergence of Weyl nodes, allowing for the direct observation of Fermi arcs via ARPES. The study also confirms the topological nature of TaAs, with Fermi arcs starting and ending at the projections of Weyl nodes. The surface electronic structure was analyzed using ARPES, revealing anisotropic features and a complex Fermi surface. The results are consistent with theoretical predictions, confirming the existence of Weyl nodes and Fermi arcs in TaAs. The study provides strong evidence for the Weyl semimetal phase in TaAs, making it a promising material for studying topological quantum states. The research also highlights the importance of ARPES in observing the unique properties of Weyl semimetals.This paper reports the experimental discovery of Weyl semimetal TaAs through angle-resolved photoemission spectroscopy (ARPES). The researchers observed Fermi arcs on the surface of TaAs, which are a hallmark of Weyl semimetals. These arcs connect projections of Weyl nodes with opposite chirality on the surface. First-principles calculations confirmed that TaAs is a Weyl semimetal, with a dozen pairs of Weyl nodes in the Brillouin zone. The absence of inversion symmetry in TaAs's crystal structure leads to the emergence of Weyl nodes, allowing for the direct observation of Fermi arcs via ARPES. The study also confirms the topological nature of TaAs, with Fermi arcs starting and ending at the projections of Weyl nodes. The surface electronic structure was analyzed using ARPES, revealing anisotropic features and a complex Fermi surface. The results are consistent with theoretical predictions, confirming the existence of Weyl nodes and Fermi arcs in TaAs. The study provides strong evidence for the Weyl semimetal phase in TaAs, making it a promising material for studying topological quantum states. The research also highlights the importance of ARPES in observing the unique properties of Weyl semimetals.