In law, interrogatories are a formal set of written questions propounded by one litigant and required to be answered by an adversary, in order to clarify matters of evidence and help to determine in advance what facts will be presented at any trial in the case.
The vast majority of such questions are to find background information about the litigants that is not specific to each case, so it is common to use pre-printed forms containing standard questions that are generally relevant to the type of case at hand, called form interrogatories. These may even be determined by statute or court rules.
Interrogatories are just a set of questions typically posed to an adverse party in litigation.
This distinguishes your responses to interrogatories from responses to requests for production of documents and requests for admissions, neither of which are under oath.
The interrogatory may ask you to identify all of the physicians you have seen in the last 10 years, and it may ask for their addresses, telephone numbers, charges, diagnoses, and treatments.
Interrogatories may, without leave of court, be served upon the plaintiff after commencement of the action or upon any other party with the summons and petition or after service of the summons and petition on that party.
Each interrogatory shall be answered separately and fully in writing under oath, unless it is objected to, in which event the objecting party shall state the reasons for objection and shall answer to the extent the interrogatory is not objectionable.
Interrogatories inquiring as to the names and locations of witnesses, or the existence, location and custodian of documents or physical evidence shall be construed as one interrogatory.