This article provides a comprehensive review of barium titanate (BaTiO₃)-based piezoelectrics, covering their fundamentals, current status, and future perspectives. The authors discuss the essential crystallographic, thermodynamic, and conceptual aspects necessary to understand piezoelectricity and ferroelectricity in BaTiO₃. They also explore strategies to optimize piezoelectric properties through microstructure control and chemical modification. The synthesis, microstructure, phase diagrams, and functional and mechanical properties of various solid solution systems, including (Ba,Ca)(Zr,Ti)O₃, (Ba,Ca)(Sn,Ti)O₃, and (Ba,Ca)(Hf,Ti)O₃, are systematically reviewed. The technological relevance of these materials is assessed, and potential market indicators are outlined. Finally, the article presents future research directions and promising areas for application, highlighting the challenges and opportunities in the field.This article provides a comprehensive review of barium titanate (BaTiO₃)-based piezoelectrics, covering their fundamentals, current status, and future perspectives. The authors discuss the essential crystallographic, thermodynamic, and conceptual aspects necessary to understand piezoelectricity and ferroelectricity in BaTiO₃. They also explore strategies to optimize piezoelectric properties through microstructure control and chemical modification. The synthesis, microstructure, phase diagrams, and functional and mechanical properties of various solid solution systems, including (Ba,Ca)(Zr,Ti)O₃, (Ba,Ca)(Sn,Ti)O₃, and (Ba,Ca)(Hf,Ti)O₃, are systematically reviewed. The technological relevance of these materials is assessed, and potential market indicators are outlined. Finally, the article presents future research directions and promising areas for application, highlighting the challenges and opportunities in the field.