In Alagaësia, a person's worth and property was largely determined by what they inherited from the previous generation, especially those that are of a lower social standing. Smiths, for example, inherited tools from their fathers or whatever smith preceded them. To clarify issues regarding inheritances, there are several Terms of Heritage that determine what a child inherits.
- Eldest: The eldest or firstborn was whichever child was born first, especially in the case of having two or more younger siblings. Murtagh Morzansson and Roran Stronghammer were both considered to be "eldest," though Murtagh had only one younger sibling, and Roran had none.
- Heir: When a child was designated to receive a certain inheritance, they were called the heir. Heirs in Alagaësia were likely separated into heirs apparent and heirs presumptive, with the former having the stronger claim. Heirs were usually the eldests, but younger siblings may have receive inheritances as well, especially if the actual eldest is illegitimate.
- Elder: Elder was a generic term for an heir that had at least one younger sibling, but was not the firstborn. Elder could also have been used to signify the eldest in a group of two siblings.
- Younger: Younger was a generic term for an heir that had at least one elder sibling, but was not the youngest. Younger could also have been used to signify the youngest in a group of two siblings.
- Youngest: Youngest was a term for an heir that had elder siblings and no younger siblings, especially if they had more than one elder sibling.
- Sole heir: The sole heir or only child was an heir that had no siblings, and thus inherited everything by default. Roran Stronghammer and Katrina Ismirasdaughter were both sole heirs.
- Legitimate: Legitimate was a term for a child who was born inside of wedlock, i.e. their parents were married when they were born.
- Bastard: Bastard or illegitimate heir was a term for a child who was born outside of wedlock, i.e. to parents who were not married. Eragon, along with all elves, were technically bastards.
- Disinheritance: A parent could choose to disinherit a child that had caused them grief, cutting them off from what would normally be their rightful inheritance. Sloan chose to disinherit Katrina after she decided to marry Roran, despite his not approving the union and Roran not seeking his blessing.