A more thorough explanation:

The doctrine of completeness is a rule under the Federal Rules of Evidence that requires the introduction of any other parts or any other writing or recorded statement that ought to be considered contemporaneously with the writing or recorded statement originally introduced. This rule is to ensure that the jury views the incomplete statement in its full context.

For example, if a party introduces a portion of a conversation as evidence, the opposing party can request that the entire conversation be introduced to provide context and clarity. This additional evidence is called explanatory evidence, and its purpose is to qualify, explain, or put the original piece of introduced evidence in context.

Furthermore, the doctrine of completeness allows otherwise inadmissible evidence, such as hearsay, to be admissible if it is necessary to correct any confusion or wrongful impression created by the admission of the original evidence. For instance, if a witness testifies about a conversation they had with someone else, and only a portion of that conversation is introduced as evidence, the opposing party can request that the entire conversation be introduced to provide a complete understanding of the conversation.

In summary, the doctrine of completeness ensures that all relevant evidence is presented to the jury to provide a complete and accurate understanding of the evidence presented.