Interrogatory
Interrogatories are merely written questions served (some use the term "propounded") to any other party that are to be answered separately and fully in writing under oath, unless it is objected to, in which event the reasons for objection shall be stated in lieu of an answer [and signed by the attorney making them].
Oftentimes in litigation involving a corporation, partnership, agency, or other business entity, an interrogatory may be answered just as well by the issuing party's examination of actual business records as it could be answered by a written answer from the business served with the interrogatory.
The most well-drafted sets of interrogatories normally contain some sort of prefatory language setting forth special instructions to be followed by the served party. These instructions will most likely reference, if not explicitly state, the applicable deadline for answers (generally the deadline is 30 days after service in both state and federal court, although there are methods by which this timeline can be changed) and will state the place where service of such answers and production of any applicable documents are to occur. It may also be in the legal professional's best interest to include language in the instructions that places the served party on notice that the discovery requests are continuing in nature and should be supplemented when new, additional, or corrected information comes to light. Another important item to include is an instruction requiring the answering party to disclose any information withheld, the source of the information, and the basis for withholding it (this will help to determine the sufficiency of any objections raised).
A thorough set of interrogatories will also include a definitions section wherein certain words used in the interrogatories themselves are explained in greater detail in order to help streamline the form and "readability" of the interrogatories.