Nobles receive their status either from birth or from the largesse of a king or lord.

In theory, the youngest son is followed in the line of succession by the eldest daughter, after whom come her sisters in birth order.

It is unclear whether women can inherit in their own right in the Iron Islands.

An otherwise weak claim may also be secured by the sword.

Robert I Baratheon was chosen as the leader of the rebellion because of his Targaryen descent, but he only became king because the rebellion succeeded. lord of a certain place) and lands are passed on within families; knighthood is not inherited but is conferred on individuals independently due to merit, not birth.

The last time a Great Council was convened was in 233 AC, when it chose the next king of the Seven Kingdoms, overriding the usual line of inheritance to give the crown to the youngest son of Maekar I, Aegon V, ahead of his elder brothers.

The short answer is that the laws of inheritance in the Seven Kingdoms are modelled on those in real medieval history...

which is to say, they were vague, uncodified, subject to varying interpretations, and often contradictory.

A man's eldest son is his heir, followed by his second son, then his third son, and so on.

In the Great Houses, where elder siblings inherit a significant title and lands, small holdings and keeps may be granted to their younger brothers, who hold their lands as bannermen.

A lord may lay out specific terms for inheritance or pass over their offspring in his will, which may invite legal wrangling after their death, and potentially violence during it.

For instance, Lord Tywin Lannister wants his elder son, Ser Jaime, to be his heir to Casterly Rock and refuses to acknowledge the claim of his younger son, Tyrion, despite custom disqualifying Jaime as a member of the Kingsguard.