Subpoenas are a type of discovery where we can get information and documents from non parties — people or companies who are not in the lawsuit.
The other types of discovery we have discussed so far — initial disclosures, interrogatories, request for production, and request for admissions — are only to the parties in the case. The Plaintiff (who filed the case/lawsuit) and the Defendant (who was sued and who has answered the lawsuit).
Why would we use a subpoena?