A witness is a person who testifies under oath in a trial or a deposition in the lawsuit. The plaintiff or defendant may be a witness. Witnesses have first-hand knowledge about matters relevant to the case and their testimony is subject to the applicable rules of evidence. A lay witness is an ordinary person who testifies based upon their personal knowledge and life experiences. An expert testimony testifies based upon their qualifications of expertise in their field.
Witness may also be used to refer to the act of observing the signing of a document like a will or a contract and signing as a witness on the document attesting that the document was signed in the presence of the witness. Should the document later be called into question, the witness may be called to testify to its making.
