A more thorough explanation:

Definition: Exacta diligentia is a Latin term used in Roman law that means great care or diligence.

In Roman law, diligentia refers to the level of care or diligence that a person is expected to exercise in their affairs. There are two standards of diligence: a higher standard and a lower standard. The higher standard is called diligentia exacta or exactissima, which is the extraordinary diligence that a head of a family habitually exercises in business. The lower standard is called diligentia quam suis rebus, which is the level of diligence that a person of ordinary prudence exercises in their own affairs.

For example, if a person is contractually obliged to look after another's interests, they are expected to exercise diligentia exacta or extraordinary diligence in fulfilling their obligations. If they fail to do so, they may be held liable for any damages or losses incurred by the other party. On the other hand, if a person is only responsible for their own affairs, they are expected to exercise diligentia quam suis rebus or ordinary diligence.

Overall, exacta diligentia emphasizes the importance of great care and attention to detail in fulfilling one's obligations and responsibilities.