A more thorough explanation:

Extinguishment of legacy is also known as ademption. It refers to the situation where a gift made in a will cannot be given to the beneficiary because it no longer exists or is no longer part of the estate at the time of the testator's death. There are two theories of ademption: the identity theory and the intent theory.

The identity theory of ademption means that if a specific piece of property is not part of the testator's estate upon their death, then the gift will fail. For example, if a testator leaves a specific painting to their niece, but the painting is sold before the testator's death, then the niece will not receive the painting.

The intent theory of ademption means that if a specific devise is no longer in the testator's estate at the time of their death, the beneficiary will receive a gift of equal value if it can be proved that the testator did not intend the gift to be adeemed. For example, if a testator leaves a specific piece of property to their niece, but they sell the property and use the proceeds to buy a different property, the niece may still receive a gift of equal value if it can be shown that the testator intended for them to receive something of equal value.

There are two types of ademption: ademption by extinction and ademption by satisfaction. Ademption by extinction occurs when the unique property that is the subject of a specific bequest has been sold, given away, or destroyed, or is not otherwise in existence at the time of the testator's death. Ademption by satisfaction occurs when the testator, while alive, has already given property to the beneficiary in lieu of the testamentary gift.

For example, if a testator leaves a specific car to their nephew, but the car is destroyed in an accident before the testator's death, then the nephew will not receive the car. This is an example of ademption by extinction. On the other hand, if a testator leaves a specific car to their nephew, but they give the nephew a different car while they are still alive, then the nephew may not receive the specific car mentioned in the will. This is an example of ademption by satisfaction.