Acid reflux, also known as gastroesophageal reflux (GER), is the backward flow of stomach acid into the esophagus, because the muscle that controls the passage between the esophagus and stomach doesn’t close completely. Acid reflux can cause sore throats, hoarseness, and heartburn. When acid reflux produces chronic symptoms, such as frequent heartburn, it is known as gastroesophageal reflux disorder (GERD).
Reference:
AMA: https://www.ama-assn.org/
Mayo Clinic: https://www.mayoclinic.org/diseases-conditions/heartburn/expert-answers/heartburn-gerd/faq-20057894
NIH: https://www.niddk.nih.gov/health-information/digestive-diseases/acid-reflux-ger-gerd-adults
Harvard: https://www.health.harvard.edu/digestive-health/9-ways-to-relieve-acid-reflux-without-medication