According to Vajrayana Buddhism Tara is a completely enlightened Buddha that typically appears in the form of a beautiful youthful woman sixteen years of age. By category and hierarchy Tara is a Meditational Deity (yidam) and her appearance is that of a peaceful deity which is synonymous with Devi and Bodhisattva Appearance - one of the Eleven Figurative Forms in Tibetan art.
The most common forms of Tara are the green which is considered special for all types of activities, white for longevity and red for power. The different forms of Tara come in all colours, numbers of faces, arms and legs, peaceful, semi-peaceful and wrathful. There are simple meditational forms representing a single figure and then there are complex forms with large numbers of retinue figures filling all types of mandala configurations. There are likely to be close to two hundred different meditational forms of Tara.
Jeff Watt 2-2003 [image added 2-2014]