Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

Cyclopedia of the Realms-page 9 wrote:A few local greetings and farewells are given hereafter, for use by the traveler.
--Well met — - The most often used greeting, particularly between strangers of a different race or those of whom one is unsure.
--Well again — - Between business associates or acquaintances, (i.e. we’'ve greeted before—hence the "“again" -’‘—and you look well) is usually used; if one is annoyed, curt, or sarcastic, one usually just says, “"Again"” (i.e. “"we meet again"” or “"you again!“")
--Olore'’ (Oh—LOR-ay—“ "Well met”"/“"Good day"”), as travelers in the Inner Sea lands say; “"Olore’' to you, my friends."”
--Until swords part— - Warriors'’ farewell throughout the Realms.
--Until next, may your sword be ever wet, and your bottom dry —- the pirates of the Inner Sea.
--Alavairthae! (Al-ah-VARE-thay—“ - "May your skill prevail”")— - the Red Wizards of Thay, in giving their farewells.
--Amarast! (Ah-mah-RAST - "—Fare well until next we meet!")— - the sailors of the South.
--Sweet water and light laughter - until next —the People (Elves).
--Aluve (Ah-LOO-veh "—I/we leave you")— - the Drow.
--Axe high, friend. I go. —- Dwarvish farewell.
--Forges warm, friend. —- Gnomish farewell.
--Good morning, and good day after that! Don’t let anything curl your hair! (to which is sometimes added—...) ’'Ware that Big Folk, and mind the goblins too!, as the Halflings speak to each other—... to others, they usually say, ’Gods smile! (upon you) /(for others rarely have the patience for the longer form).
--Braeunk vhos trolkh! (If you die while I’m gone, do it quietly)— - Hobgoblin, with the unspoken addendum “"because I wouldn’'t want to miss the fun."”

FR Campaign Setting-page 84 wrote:

Language

Common language and culture defines a state just as much as borders, cities, and government do. Each major nonhuman race speaks its own language, and humans seem to generate dozens of languages for no other reason than their lands are so widespread and communications so chancy that language drift occurs over time. Hundreds of human dialects are still spoken daily in Faerun, although Common serves to overcome all but the most overwhelming obstacles to comprehension.

The oldest languages spoken in Faerun are nonhuman in origin. Draconic, the speech of dragons, may be the oldest of all. Giant, Elven, and Dwarven are also ancient tongues. The oldest known human languages date back some three to four thousand years. They come from four main cultural groups—Chondathan, Imaskari, Nar, and Netherese—that had their own languages, some of which survive today in altered forms after centuries of intermingling and trade.

THE COMMON TONGUE

All speaking peoples, including the humans of various lands, possess a native tongue. In addition, all humans and many nonhumans speak Common as a second language. Common grew from a kind of pidgin Chondathan and is most closely related to that language, but it is far simpler and less expressive. Nuances of speech, naming, and phrasing are better conveyed in the older, more mature languages, since Common is little more than a trade language.

The great advantage of Common, of course, is its prevalence. Everybody in the Heartlands speaks Common well enough to get by in any but the most esoteric conversations. Even in remote areas such as Murghom and Samarach, just about everybody knows enough Common to speak it badly. They might need to point or pantomime in a pinch, but they can make themselves understood. Natives of widely separated areas are likely to regard each other's accents as strange or even silly, but they still understand each other.