The Fingers is a region on the east coast of the Vale of Arryn, located along the shores of the Narrow Sea. It consists of four long, slender peninsulas extending into the sea, divided by bays, inlets and channels. House Baelish rules over the smallest of the Fingers.
For this reason, its current lord, Petyr Baelish, is popularly called 'Littlefinger'.
In the books
In the A Song of Ice and Fire novels, the Fingers are lonely, cold and windswept. House Baelish maintains a small, unassuming tower on the smallest of the Fingers. The Andals landed on the Fingers during their invasion of Westeros and weathered stones bearing the symbol of the Faith of the Seven can be found dotted along the shore in some areas.
Mountains of the Moon · The Fingers
The Bite · The Fingers