Free Companies are "guilds" in the words of other MMOs. Keep in mind that we have in-game guilds as well, such as the Archers' Guild, Adventurers' Guild, etc, so we don't really call FCs guilds in XIV. xD Confusion would ensue. You are allowed to join one FC, and there are in-game perks associated with it (housing, rankings, some other stuff we don't know of yet).
Linkshells are actual items that exist in Eorzea that are used to communicate over distances. Think of them like a constant conference call. They're small enough to be worn on an earring and you are able to speak to other pearl-holders and hear them in return. In 1.0, these were all we had. They are used OOCly for social and endgame purposes, though I suspect more endgame pearls will be going to FCs, and ICly as ways to communicate with each other!Â
Linkshells are actual items that exist in Eorzea that are used to communicate over distances. Think of them like a constant conference call. They're small enough to be worn on an earring and you are able to speak to other pearl-holders and hear them in return. In 1.0, these were all we had. They are used OOCly for social and endgame purposes, though I suspect more endgame pearls will be going to FCs, and ICly as ways to communicate with each other!Â