Server

A game server (sometimes host or shard) is a server which is the authoritative source of events in a multiplayer video game. The server transmits enough data about its internal state to allow its connected clients to maintain their own accurate version of the game world for display to players. They also receive and process each player's input. (from )

DDO game servers
DDO currently has 8 distinct persistent game worlds (servers).
 * Argonnessen
 * Cannith
 * Ghallanda
 * Khyber
 * Orien
 * Sarlona
 * Thelanis
 * Wayfinder (used to be a German language recommended server, not anymore)

Additional servers are available temporarily:
 * Hardcore - special event server; uses the same client as regular servers
 * Lamannia - test/preview server; uses a separate client

Each server is a distinct game world. Your characters cannot see or interact with anything that happens on a different server. Your shared bank and the shared platinum vault is also restricted to characters of one server; so is the Auction House and in-game mail. Individual guilds are also tied to a server.

The servers are located in New Jersey.

Character Transfer
Transferring characters across worlds is a paid service costing per character. (see full details here).
 * The items in your inventory and (regular) bank are transferred with you.
 * You the items in your reincarnation cache, forever .
 * Account-wide bank stays on the original server.
 * Accumulated favor travels with you; however, per-server benefits unlocked by favor do not transfer.
 * If you want to return to your original world, you must wait at least 14 days.
 * Your guild loses 10% of your accumulated renown - same as if you deleted the character.
 * Monster Manual rewards (ability to see HP as well as any pets) stay on your original server.
 * Your Astral Shard balance stays on your original server.
 * A guild leader can not server transfer. They must hand guild leadership to someone else to enable transfers.
 * A basic rule of thumb: Anything character specific with the exception of the reincarnation cache will move with you.  Anything shared between characters, and this includes Companions and your Monster Manual Account Deeds in addition to the things listed above, remains behind.

Account-wide/across servers

 * Your game account allows you to access/create characters on all live servers, as well as the Lamannia test server.
 * Your DDO Point balance.
 * The benefits of your account type and account upgrades purchased from the DDO Store (such as adventure packs or premium races/classes).

Server-dependent

 * Your Astral Shards balance.
 * Any perks that you unlock by favor, such as 32 point builds, favor-unlockable races and classes.