Elven society is a Caste system.
The Trueblood Elves are demi-gods in the society, set apart and served by even the Firstborn. Every Elven community will have at least one Trueblood. The larger the community, the greater the number of Trueblood Elves. These immortals sequester themselves in well-protected fortresses. The Trueblood Elves are the great Faecrafters of the land, locking themselves away to research and dabble in powerful enchantments. For example, in Caranta City, the Enclave of the Trueblood is a small city-state within the bounds of the larger Elven city. The Enclave is protected by powerful and alien magics, conjured elemental monsters and deadly traps. There are about 80 Trueblood in the Enclave who are served by no less than 500 Elves (more than a dozen Firstborn among them). In Shadowood, where the communities are smaller, the largest city has only 14 Trueblood, and most communities have only one or two. Still, the fortresses they hide in, while generally smaller (perhaps a tower or a keep or an underground fortress), are nearly impregnable.
The Firstborn are the nobles of Elven society. These Elves are tremendously long living, but not immortal. This is the ruling class (in deference to the Trueblood, of course, though rarely do they deign to consider mortal affairs).
The Garan are the children of the Firstborn, the Elven middle class. This is the caste that has any contact with the outside world (generally). They are the soldiers, merchants, scholars and priests.
The Tainted are those with "other mortal blood" - the mixed races. Half-elves. Generally, the Tainted are the lowest class in Elven society, the slave labor. This is not a large percentage of Elven society, yet they shoulder the greatest burden.