1. The parties refer to the victims, private prosecutors, criminal suspects, defendants, plaintiffs and defendants in incidental civil actions.
2. The legal representative refers to the client's parents, adoptive parents, guardians and representatives of organs and organizations responsible for protection.
3. An agent ad litem refers to the victim of a public prosecution case and his legal representative or close relative, the person entrusted by the private prosecutor and his legal representative in a private prosecution case to participate in the litigation on his behalf, and the person entrusted by the party involved in an incidental civil litigation and his legal representative to participate in the litigation on his behalf.
4. Defender refers to the person who is entrusted by the accused or appointed by the people's court to help the criminal suspect and defendant exercise their right to defense in order to safeguard their legitimate rights and interests.
5. A witness refers to a person who knows the case outside the litigation and the parties.
Legal basis: Article 108 of the Criminal Procedure Law of People's Republic of China (PRC). The meanings of the following terms in this Law are:
(1) "Investigation" refers to the work of public security organs and people's procuratorates to collect evidence and ascertain the facts of criminal cases and the relevant compulsory measures taken according to law;
(2) "Parties" refer to victims, private prosecutors, criminal suspects, defendants, plaintiffs and defendants in incidental civil actions;
(3) "Legal representative" refers to the parents, adoptive parents and guardians of the client and the representatives of the organs and organizations responsible for protection;
(4) "Participants in litigation" refers to the parties, legal representatives, agents ad litem, defenders, witnesses, expert witnesses and translators;
"Agent ad litem" refers to the victim of a public prosecution case and his legal representative or near relative, the person entrusted by the private prosecutor and his legal representative in a private prosecution case to participate in the litigation on his behalf, and the person entrusted by the party involved in an incidental civil litigation and his legal representative to participate in the litigation on his behalf;
(6) "Close relatives" refer to husbands, wives, fathers, mothers, sons, daughters, brothers and sisters.