According to nolopress the definition of deposition is, “An important tool used in pretrial discovery where one party questions the other party or a witness in the case. Often conducted in an attorney's office, a deposition requires that all questions be answered under oath and be recorded by a court reporter, who creates a deposition transcript. Increasingly, depositions are being videotaped. Any deponent may be represented by an attorney. At trial, deposition testimony can be used to cast doubt on a witness's contradictory testimony or to refresh the memory of a suddenly forgetful witness. If a deposed witness is unavailable when the trial takes place -- for example, if he or she has died -- the deposition may be read to the judge in place of live testimony.”
Deposition is a last resort if you are a Pro Se Litigant due to the expense. You have to pay a court reporter for their time, pay for the transcript from the deposition, you will have to pay for the services of an attorney or paralegal because most states do not allow depositions to be taken by anyone other than court personnel. If you find you need to depose a witness who is not able to be present in court research your states rules of civil procedure regarding depositions. Luckily, for most Interrogatories, Requests for Production, Disclosures and Admissions of Fact produce any documents or evidenc you will need at the time of your divorce court hearing.