What the Age will consist of depends on what Symbols are contained within the book used to link to it.
To generate an Age, the player must either use, a blank Descriptive Book (the symbols will be selected randomly) or, if a player wants to customize their own age, they can use a Writing Desk to copy symbols to and from their personal Notebook and then write their own Age using the Book Binder.
To travel to a new Age, players must Link by using the Descriptive Book used to generate it or a Linking Book crafted inside the Age, either from a Held Book or a stand. The player will be transported to the Age with their inventory and experience, but the book will not travel with them. If the book was on a stand then it will remain there. If the book was in the player's inventory, it will fall to the ground, open. Books on stands can only take damage from rain and snow, while books on the ground will also take damage from water and anything that can hurt an entity such as a player. Books on the ground also take damage over time, so a covered book stand is the safest way to store a book.
Players must be wary when traveling between ages: in order to return to their previous age, the player will need a Linking Book created in the exact place they would like to return to. If a player forgets their Linking Book, they will usually be trapped with no way back to where they started. Their only hope is to find a Star Fissure to get back to the Overworld spawn. Another way to get out of an Age is to cheat, by using NEI to give yourself a portal block, and using it to travel to the Nether. Once in the Nether, the player can create another portal and go back to the overworld.
Ages may also be unstable, leading to Decay. Decaying ages will fall apart around the player, eventually leading to a full collapse. Players must always be wary of shifting earth, as there is no other form of warning. Unstable ages are very difficult if not impossible to stabilize, though Skylands ages are more resilient to Decay.