Many things. For many, prevention = avoiding fried/oily foods, peppermint, chocolate, cheese, tomatoes, alcohol, nicotine, spicy foods, black pepper, orange juice, eating <4 hrs before bedtime. Raising head of bed 6in can help. Course of otc h2 blocker (eg. Ranitidine) or ppinhibitor (eg. Omeprazole) can help. If pain/difficult swallowing, wt loss, no appetite, or no improvement, better see doc; those can be warning signs.