What is Exhibit?

Legal Definition
An exhibit, in a criminal prosecution or a civil trial, is physical or documentary evidence brought before the jury. The artifact or document itself is presented for the jury's inspection. Examples may include a weapon allegedly used in the crime, an invoice or written contract, a photograph, or a video recording.

The main concept behind correct evidence handling is that the item recovered is the same as that produced in the court room.

The usual term applied to such handling is "chain of custody". The term denotes the links in the handling of the exhibit in question. For example, details of the item, the place, date, time it was recovered, and by whom it was recovered - the first link. The subsequent links in the chain refer to anyone required to handle the exhibit, mainly for identification purposes. The final link is the production of the item in court. This particular level of auditable handling is paramount when dealing with items of a forensic nature, as it reduces the opportunity for the defense to challenge the authenticity of the item.

The chain of custody can be less stringent when dealing with property which has a unique identifying feature like a serial number. In such a case, the physical security becomes the main concern of the person recovering the item. Such security is normally achieved by booking the item into a central evidence room.

The exhibits in any one law case are often labelled Exhibit A, Exhibit B, Exhibit C, etc. to distinguish between them.
-- Wikipedia
Legal Definition
Practice. Where a paper or other writing is on motion, or on other occasion, proved; or if an affidavit to which the paper writing is annexed, refer to it, it is usual to mark the same with a capital letter, and to add, " This paper writing marked with the letter A, was shown to the deponent at the time of his being sworn by me, and is the writing by him referred to in the affidavit annexed hereto." Such paper or other writing, with this attestation, signed by the judge or other person before whom the affidavit shall have been sworn, is called an exhibit. Vide Stra. 674; 2 P. Wms. 410; Gresl. Eq. Ev. 98.
-- Bouviers Law Dictionary
Legal Definition
To produce a thing publicly, so that it may be taken possession of, or seized. Dig. 10, 4, 2. To exhibit means also to file of record; as, it is the practice in England in personal actions, when an officer or prisoner of the king's bench is defendant, to proceed against such defendant in the court in which he is an officer, by exhibiting, that is, filing a bill against him. Stepb. P.I. 52, n. (1); 2 Sell. Pr. 74. In medical language, to. exhibit signifies to ad minist er, to cause a thing to be taken by a patient. Chit. bled. Jur. 9.
-- Bouviers Law Dictionary
Legal Definition
v. To show or display; to offer or present for inspection. To produce anything in public, so that it may be taken into possession. Dig. 10, 4, 2. To present; to offer publicly or officially; to file of record. Thus we speak of exhibiting a charge of treason, exhibiting a bill against an officer of the king's bench by way of proceeding against him in that court. In re Wiltse, 5 Misc. Rep. 105, 25 N. Y. Supp. 737; Newell v. State, 2 Conn. 40 ; Comm. v. Alsop, 1 Brewst. (Pat) 345. To administer; to cause to be taken; as medicines.
-- Black's Law Dictionary
Legal Definition
n. A paper or document produced and exhibited to a court during a trial or hcaring or to a commissioner taking depositions or to auditors, arbitrators, etc., as a voucher or in proof of facts or as otherwise connected with the subject-matter, and which, on being accepted, ls marked for identification and annexed to the deposition, report or other principal document or filed of record or otherwlse made a part of the case. A paper referred to in and filed with the bill, answer, or petition in a suit in equity, or with a deposition. Brown v. Redwyne, 16 Ga. 68.
-- Black's Law Dictionary
Legal Definition
Any paper or thing offered in evidence and marked for identification; an instrument or copy thereof attached to a pleading and by reference incorporated in it. See 16 Ga. 67; to offer in evidence as an exhibit.
-- Ballentine's Law Dictionary