Song is an ActionClassification which means that every Song card is also an Action card and can be played just like any other Action card by paying its cost and resolving its effect. However, a player can also play the Song without paying its cost by Exerting a Character with equal or greater Ink cost than the Song's Cost. This is referred to as that character singing the song. During the player's turn Main Phase Songs must be resolved in the moment they are played, thus effects of other elements in play must be resolved in any order before and after playing the Song. Abilities must be resolved in the text's order.
Characters that were just played are unable to Exert on the turn that they were played. As such, Characters cannot sing for a Song card until the following turn after they were played. Characters with the Singerkeyword are able to sing songs that are higher costs than their own costs, up to the Singer number.
Songs have a clear synergy with Amber Ink, offering the most interactions with Character of said Ink.