Cardiac resynchronization therapy is an established device-based treatment for selected patients with heart failure and electrical dyssynchrony. By coordinating right and left ventricular contraction, CRT improves cardiac output, reverses adverse ventricular remodeling, reduces symptoms, and lowers hospitalization risk. The greatest benefit is observed in patients with reduced left ventricular ejection fraction, widened QRS duration, and left bundle branch block morphology. This article reviews indications, patient selection, procedural considerations, clinical outcomes, complications, and future directions of CRT in heart failure management.