Old families, elven

Concept of the "Old families" is most used among high elves and eladrin, but also sea elves and even some wood elves are very aware of the concept. Llothian drow societies believe in to old family lines as well, but as their society doesn't promote stability, the concept is far more muddy.
When elves refer to "old families", they refer to long and ancient family lines that can be followed back to countless generations, often having a colorful history and great significance in their respective communities.

Old families and social ranking

A common misconception by outsiders is that Old families are somehow connected to royal or at least noble bloodlines, but this isn't always the case, not even most of the time. Most elven nobles do, indeed, come from old families, yet nobility isn't required in the concept. Old families tend to have a long line of well-established members like scientists, master craftsmen, warriors, mages, scholars, benefactors, explorers, and even great artists - these are people that have brought significant value to people around them and written long history to be proud of.
With a long prestigious history, members of Old Families are treated with respect and reverence, giving them social status and say to their communities. Respect, however, is something to be maintained - name only had power as long as the family keeps producing worthy decedents. Not every member has to be better or even match their legendary ancestors; more important is, that family members strive to be better and respect their family legacy.
Members of most prestigious old families are considered suitable matches to elven nobility, without feeling that they needed to "downgrade", to a point were most well established old families, even without titles of their own, might find lowest nobles as "downgrade" to their position.