A more thorough explanation:

Necessaries are essential items required for a person to live a healthy and comfortable life. The things that are considered necessary may vary depending on a person's socio-economic status, background, and standard of living. Some examples of necessaries include:

• Food
• Habitation (shelter)
• Medical treatments
• Legal services

The doctrine of necessaries is a legal concept that holds a spouse responsible for the costs and expenses incurred for the well-being of the other spouse. This doctrine is based on the common law idea that a husband must provide for his wife and children during an ongoing marriage. Today, this doctrine is gender-neutral and applies to both spouses. It is usually used in the medical context, where a party can establish a case for the recovery of expenses incurred in providing necessary medical services for the other spouse, even if the spouse did not sign as a guarantor or request for the other spouse to be admitted.

For example, in North Carolina, where the doctrine of necessaries applies, if one spouse requires medical treatment, the other spouse may be held responsible for the costs of that treatment, even if they did not agree to it beforehand.