In GIS, Identity is a overlay operation commonly used in GIS software. It allows the user to combine the attributes of one overlapping feature into another. The Identity overlay takes two or more layers and gives any intersecting areas of layers with a target or "identity" layer, the characteristics of the identity layer. In other words, the Identity method preserves only the features that fall in the the area extent of the input layer. Also included is the attribute information in the database of the overlapped portion of identity feature over the input feature will be merge with the input's attributes.
In ArcGIS, the Identity operation is found in the Overlay toolbox. The Identity operation needs an input and an identity feature. The input feature can either be a point, multipoint, line, or a polygon. As for the identity feature, the feature can only be a polygon unless the input and identity features have the same geometry type. 
An example of Identity includes a road that is in two different counties. The results would be two different features and both would include the attributes of the road and the county it passes through. 
- "Identity (Analysis)", ArcGIS Desktop 10.2 online help, Accessed 11 September 2013.
- "GIS Dictionary: Identity", ArcGIS Support GIS Dictionary, Accessed 11 September 2013.