Which of the following best describes "joinder"?

Joinder refers to the combining of claims or parties in a single lawsuit, which is accurately captured by the chosen response. This legal concept allows multiple parties to join together in one action, or for a single party to bring multiple claims against another party, thereby promoting efficiency in the legal process. By allowing multiple claims or parties to participate in one action, joinder helps to streamline litigation and reduce the potential for inconsistent judgments, as related issues can be addressed simultaneously.

In this context, other options do not reflect the true nature of joinder. Dismissal of parties from a case contravenes the idea of joinder, as it involves removing rather than combining parties. The splitting of legal issues across jurisdictions relates more to jurisdictional issues rather than the joining of parties or claims. The process of appealing a court's decision also does not pertain to joinder, as it involves a review of a decision rather than the initial consolidation of claims or parties.