Guild is a common and important feature in Rift US, to form it, you will need 5 people and 1 platinum. If you are new in game and want to form a guild, simply hail one of the guild charter NPCs, and pick a name. It will invite you, then you will need to invite 4 other people, they do not have to be grouped. In Rift, guilds level up by earning experience points, similar to the way that players do. As levels are gained points are earned, these points can then be spent on various upgrades known as perks. The only way to earn guild experience is through various quests that high ranking guild officials can accept on behalf of the members.
When you play guild in rift mmo (US), you will know it has many functions, such as Roster, Rankings, Flags, Levels, Quests, Chat, and Achievements. For Roster, it shows the current player list, what calling they are, race and the zone they are in. There is a function to right click a guild member and invite them to a group; for Rankings, there are 8+ rankings from applicant to leader, and a permissions screen where you can rename the ranks and permissions; for Flags, there are flags that you can spend points buying, such as rally flags, and flags that increase power, damage, health for a set amount of time.
Besides, for Levels, there are guild levels and experience; for Quests, there are guild quests that can be picked up from the NPCs around the guild register. Quests range from kill x amount of mobs, to pvp, to dungeons; for Chat, there is guild chat and MOTD. Officers also seem to have a chat; and for Achievements, the guild does have achievements. Hope this rift guide (US) is very helpful for you.