Unlike what you see on television, you cannot have surprise witnesses or surprise documents when the case goes to trial. The prosecution and the defense must exchange any information they have in their possession that they think has a bearing on the case. According to the American Bar Association, this is the discovery process. 

Most jurisdictions have what is known as automatic discovery, which means your attorney does not need to contact the court in advance and specifically request these things. The prosecution always goes first with the exchange, and their initial discovery disclosure requires them to turn over a copy of your criminal history, the charges against you, the probable cause affidavit that support those charges and any police reports that happen to be in their possession that would have an impact on what did or did not happen in your case. There is usually more information that does get exchanged as the case proceeds forward, but that is the initial discovery that the prosecution has to turn over to you. 

Most jurisdictions have 30 days from the date that your attorney files his appearance form to turn that over to you. Your attorney, by comparison, once he receives the state’s disclosure, has 30 days to turn any similar information back over to the prosecution. The information will be about witnesses that the defense might rely on, special defenses like self-defense, an alibi that they might be relying on and things of that nature. The discovery process continues throughout the case, so you do not have to worry about asking every single time there’s new information.