What is a codicil in relation to a will?

A codicil is indeed a supplement to an existing will that includes modifications or clarifications. Essentially, it allows the testator (the person who made the will) to make changes without the need to completely rewrite their will. This could involve adding new provisions, altering or revoking previous ones, or addressing specific concerns that have arisen since the original will was created.

Using a codicil can be an efficient way to ensure that the will accurately reflects the testator's current wishes without going through the potentially more complex process of drafting an entirely new document. It's crucial, however, that the codicil is executed with the same formalities as a will, meaning it must be signed and witnessed appropriately to be legally valid.

The other options do not accurately define a codicil. A complete rewrite of the will would not fall under the definition of a codicil. A legal challenge to a will pertains to disputes over its validity or interpretation, while notarization relates to the witnessing and validation of documents rather than the function of a codicil itself.