Could you tell me what are cankersores of the mouth and how come people get them?

Apthous ulcers: Although the reason for developing these lesions remains a scientific mystery, they are small idiopathic lesions found in the softer folds of mouth tissues. There can be some tingly feeling in the area prior the arrival, and about 3 days after they erupt for them to disappear. Changes in weather, diet, and stress have been know to increase the chances of development.