"In Greek mythology, Nymphs were spirits of nature. Even though they were female divinities of lower rank, still they were revered as the protectors of springs, mountains, grottoes, trees, the sea and rivers. They were portrayed as young, pretty girls, each subtype presiding over whichever aspect of nature they represented.

Depending of where they resided, the Nymphs are as follows: Dryads (forests), Naiads (springs and rivers), Nereids (the Mediterranean), Oceanids (the sea) and Oreads (mountains), Limoniads (meadows), Limniads (lakes, marshes and swamps), Meliads (ash-trees), Epimeliads (protectors of sheep) and Napaea (valleys and glens). There are more categories of Nymphs, the names varying according to the ancient sources. (Please read below for more information on Dryads and Naiads)

The Nymphs' male equivalent are the Satyrs.

The Dryads: (Dryades, Hamadryades,) are female spirits of nature who preside over the groves and forests. Each one is born with a certain tree over which she watches - she comes into existence with it and often lives in a tree.

The lives of the Dryads are critically connected with that of their trees; should the tree perish, then she dies with it. The Dryads themselves were known to punish any thoughtless mortal who would somehow foolishly or cruelly injure the trees.

The Naiads: (Naiades) were nymphs of bodies of fresh water and were one of the three main classes of water nymphs - the others being the Nereids (nymphs of the Mediterranean Sea) and the Oceanids (nymphs of the oceans). The Naiads presided over rivers, streams, brooks, springs, fountains, lakes, ponds, wells, and marshes. They were divided into various subclasses: Crinaeae (fountains), Pegaeae (springs), Eleionomae (marshes), Potameides (rivers), and Limnades or Limnatides (lakes).

The Naiad was intimately connected to her body of water and her very existence seems to have depended on it. If a stream dried up, its Naiad expired. The waters over which Naiads presided were thought to be endowed with inspirational, medicinal, or prophetic powers. Whoever drank of these magical waters would be inspired, thus the Naiads were themselves considered prophetic and were frequently worshipped by the ancient Greeks in association with divinities of fertility and growth. Hence all persons in a state of rupture, such as madmen, poets, seers and prophets, were said to be caught by the Nymphs. " 1


1. http://www.pagerealm.com/windseeker/nymph.html