A more thorough explanation:

Term: Obiter dictum
Definition: Obiter dictum is a Latin term that means "something said in passing." It refers to a comment, suggestion, or observation made by a judge in an opinion that is not necessary to resolve the case. These comments are not legally binding on other courts, but they can be cited as persuasive authority in future litigation. Obiter dictum can also be referred to as dicta, dictum, or judicial dicta. A dissenting opinion is also generally considered obiter dictum.
Examples: In a court case, a judge may make a comment about a hypothetical situation that is not relevant to the case at hand. This comment is considered obiter dictum. For example, in the case of Trump v. Hawaii, Chief Justice John Roberts made a comment about a previous case that was not necessary to resolve the current case. He said, "Korematsu was gravely wrong the day it was decided, has been overruled in the court of history, and—to be clear—'has no place in law under the Constitution' 323 U.S., at 248 (Jackson, J., dissenting)." This comment was not necessary to resolve the case, but it may be cited as persuasive authority in future litigation.
Obiter dictum can be valuable because it can be incorporated into later opinions and sometimes even serve as the basis of those opinions. For example, in the United States v. Carolene Products case, Justice Harlan F. Stone made a suggestion in Footnote 4 that a legal rule more stringent than the rational basis test be applied in hypothetical, future situations. This suggestion eventually served as the basis for the doctrine of strict scrutiny.