Symptoms of Acidity Are:

    Pain and burning sensation in the chest, stomach or throat
    Flatulence or Gas
    Indigestion
    Bad Breath
    Constipation
    Nausea or feeling of vomiting
    Heaviness in the stomach after eating
    Frequent burps
    Regurgitation of undigested food coming back in our mouth

Common Causes of Acidity:

    Over-eating
    Eating at odd times or skipping meals
    Unhealthy eating habits like having too much tea, coffee, cold- drinks, junk, spicy, oily food etc.
    Stomach ailments like Ulcers, Gastro-oesophageal Reflux Disease (GERD), etc.
    A bad lifestyle like taking too much stress, sleeping less, smoking, drinking alcohol etc.

Acidity has been confused with other conditions, here is a quick guide to understanding these terms better: