Forgotten Realms:

Elves, much like their living ancestors, the eladrin, who were also commonly called elves, were a long-lived race of the Tel-quessir found most commonly in forests, shrublands, and other wildernesses. From time to time the elves organized strong nations, though with far less frequency than eladrin, in some cases adopting even a nomadic lifestyle. Almost all elves worshiped the gods of the Seldarine, and the elves were generally, though not always, good in nature. Elves were usually found in small tribes throughout the forests of Toril, as well as on windswept plains and in mountain vales. The elves, as a whole, preferred these secluded places of nature to the cities and nations of the civilized world, living in harmony with their natural surroundings. Cautious and cunning warriors, particularly of the bow, elves secured these homelands through guile and tactics.  

Greyhawk:

Elves of the Flanaess are a bit shorter and lighter than humans, with a slender, athletic build and typically fair complexions, although eye and hair colour can vary among the subraces. Elves are long lived and spend much time in study or exploring, giving many people the impression that they are not entirely concerned with the world around them, while others may find them a bit chaotic. They're fascinated with magic and beauty, both permanent and temporary. Once categorised into three types, sages have noted many more elven subraces; High elf being the most commonly known and most commonly encountered, with the reclusive Grey (Faerie) and Wood (Sylvan) elves second to this. Two other groups unique to Greyhawk are often confused with the latter two: Valley elves appear to be very similar to Grey elves and Wild (Grugach) elves commonly mistaken for shorter Wood elves. Drow (Black) elves were thought to be a myth until more recent history, and other elves such as Aquatic (sea) or Snow elves are still relatively unknown. Elves always use family names, to help keep track of extended family relations across the centuries. Family names in translation are usually romantic and flowery: Starglow, Silverfrond and the like. Even in their original tongue, they tend to be melodious. Half-elves and elves living near human communities may add a career or location tag to their names for ease in dealing with humans who use this nomenclature. This reflects the importance some elves place on bloodlines, especially among the nobles of their kind. Wood elves are likely to be the most numerous of the elven folk, examining censuses, reflected in how they appear to be the most fecund of elves. After this, despite their low numbers Drow, Wild and 'other elves' are the next most fertile of the elves, with High elves next and Grey elves the least.  

Eberron:

In Eberron, the elves originated in Xen'drik during the Age of Giants, where they were slaves of the Giants. Modern elves are split into many distinct cultures: the Aerenal, the Valenar, the Khorvaire elves, and the Drow of Xen'drik. Most elven cultures partake in some form of ancestor worship, though the Drow and some of the elves of Khorvaire are exceptions. The Elves of Eberron are known to be a strange and diverse people. Humans will often find elves to be as strange as they find orcs and goblins. The elves who live in Khorvaire have integrated with their human society and now have similar culture and ideology. The elves of Aerenal and Valenar have an isolationist and perhaps even xenophobic outlook, rarely interacting with other races and caring little for affairs outside their borders. Despite their views of outsiders The Valenar and Aerenal Elves are willing to trade and interact with other nations, though neither of these elven societies is especially welcoming to visitors. The Aerenal elves worship their ancestors as Deathless, lifeforms much like undead but kept alive by the positive energy of Irian. The Deathless serve as advisors and defenders and are considered by those who worship them to be divine as a whole, in the form of the Undying Court. Another group of elves found on Aerenal are the Tairnadal tribes, a warrior culture that lives in the plains of northern Aerenal. Tairnadal elves do not worship the Undying Court. Instead, they follow the Spirits of the Past. By emulating the deeds of these ancestors, they believe the spirits can live again. They do not resurrect their fallen or beloved as Deathless. The most notable Tairnadal tribe is the Valaes Tairn, who went on to found the nation of Valenar in Khorvaire. The elves of Khorvaire are as diverse as the elf race as a whole. They divide themselves by nation or by dragonmarked house and often follow the local customs. A few still hold their own race's beliefs in ancestor worship, but not to the same degree as the tairnadal or aereni. Currently, there is one elven dragonmark present in Khorvaire - the Mark of Shadow. it is divided across two houses: House Phiarlan and House Thuranni. The half-elven descendants of the elves, the Khoravar, have formed a separate community in Khorvaire. The Drow of Xen'drik don't worship their ancestors directly. Rather, they tend to hold to the preservation of their forebears' traditions. They believe nothing honors their ancestors more than by living as they did. Some Drow also worship the scorpion god Vulkoor, though some Khorvairian scholars suspect Vulkoor to merely be an aspect of The Mockery, a member of the Dark Six. Other notable tribes of drow include the Umbragen, who reside in the portion of Khyber that lies beneath Xen'Drik, and the Sulatar, who have mastered elemental binding techniques learned from the Giants. Long ago, another group of dragonmarked elves, bearing the Mark of Death, resided in Aerenal and the Lhazaar Principalities. However its bearer, House Vol, was utterly destroyed in -1600YK. The legacy of this house can still be seen in Khorvaire in the form of the Blood of Vol faith, which was founded by House Vol and its allies.