A police lineup (in American English) or identity parade (in British English) is a process by which a crime victim or witness's putative identification of a suspect is confirmed to a level that can count as evidence at trial. The suspect, along with several "fillers" or "foils"—people of similar height, build, and complexion who may be prisoners, actors, police officers, or volunteers—stand side-by-side, both facing and in profile. There is crucial information that should be conveyed to the eyewitness prior to viewing the lineup. It is necessary to inform the eyewitness that it is possible the perpetrator is not present in the lineup. The eyewitness should also be told that they do not have to choose one of the people from the lineup. Including these details has shown to result in fewer misidentifications. The lineup sometimes takes place in a room for the purpose, one which may feature a one-way mirror to allow a witness to remain anonymous, and may include markings on the wall to aid identifying the person's height. For evidence from a lineup to be admissible in court, the lineup itself must be conducted fairly. The police may not say or do anything that persuades the witness to identify the suspect that they prefer. This includes loading the lineup with people who look very dissimilar to the suspect. Alternatives The three main forms of police lineups are photographs of suspects, videos, or the original form of physically present lineups. Where photos and videos are often more practical and convenient, it is the identification where suspects are physically present that has proven to demonstrate improved identification. Photographs of the suspect and fillers can be shown to the identifier in what is called a "photo-lineup", or a "six pack". If the victim or witness successfully identifies the suspect from among the fillers, the identification is considered valid. There is some research into using other methods of photo-lineup that involve the witness sequentially viewing photographs rather than simultaneously. The sequential method is considered more accurate because it prevents the witness from looking at all the suspects and merely selecting the person that most resembles the guilty person. A "show-up" is another alternative, in which a suspect is individually shown to a witness. Many UK police forces use Video Identification Parade Electronic Recording (VIPER), a digital system wherein witnesses view video recordings of suspects and unrelated volunteers. Sequential lineup A sequential