It is also known as benign migratory glossitis, oral erythema migrans, glossitis areata exfoliativa, glossitis areata migrans, lingua geographica, stomatitis areata migrans, and transitory benign plaques of the tongue.
The top side of the tongue is covered in small protrusions called papillae. In a tongue affected by geographic tongue, red patches on the surface of the tongue are bordered by grayish white. The papillae are missing from the reddish areas and overcrowded in the grayish white borders. Whitish/yellow discoloration of the tongue is frequently due to a yeast infection. The small patches may disappear and reappear in a short period of time (hours or days), and change in shape or size. While it is not common for the condition to cause pain, it may cause a burning or stinging sensation, especially after contact with certain foods.
Src : Wikipedia