Library Computer Access and Retrieval System The Library Computer Access and Retrieval System ( LCARS or simply library computer / ship ' s library for short ) was a computer subsystem which was employed by the United Federation of Planets as the primary method of interacting with and operating a computer . It was used aboard Starfleet vessels , starbase s , and space station s . ( ) LCARS was accessible virtually anywhere in a facility or starship by both voice and keypad commands via control interface s . These interfaces included bridge stations , console s , PADD s , tricorder s , and desk computers . Typically , these were graphical controls housed underneath touch - sensitive clear panels that could be quickly reconfigured by users to suit the task at hand . There were also tactile interface s for visually - impaired officers . ( ; ) LCARS used sophisticated subroutine s in order to understand and execute vocal natural language commands . This enabled even complicated tasks to be executed with just a few commands in the case of voice or button presses in the case of keypad commands . LCARS controlled the retrieval and storage of files in the data banks housed within the ship ' s computer core s including log s like personal log s or transporter log s , element and chemical compound data and data on archaeological artifact s . ( ) It was used to retrieve files in external database s like when a ship needs to assess traffic control around starbases or investigate inventory databases of surplus depots . ( ) It was also used for command system access and for viewing the crew manifest . ( ) It was also used to display recently recorded data like medical scans , tactical scans and sensor scans . ( ) It displayed results of analyses like linguistic analyses , configuration analyses of system networks , and magnetic flux density analyses . ( ) Depending on the starship , the LCARS design , especially the color scheme , differed . These colors could range from a yellow / white ( found on the ) to blue / white scheme ( found on the ) . ( ; ) " In the alternate timeline of the Anti - time future around 2395 , LCARS was still used and similar in appearance to its mid - 24th century version . " ( ) " In an alternate timeline , by the 25th century , LCARS was further upgraded with three - dimensional control interfaces . " ( ) By the 29th century the LCARS was , at least partially , replaced by the TCARS . ( ) " In the alternate reality , in the 2250s , PCAP was the equivalent of LCARS . " ( ; ) Appendices . Background information . LCARS interfaces are seen in almost every episode of , , and . The interfaces seen in and are never named and their designs are quite different . A close - up view of one of the science stations aboard the " Enterprise " - D in " The Vengeance Factor " has the label " Library Computer Subsystems " . The full name " Library Computer Access and Retrieval System " can be seen in several episodes , including , and . The sickbay used in is a minor redress of the TNG sickbay , and the LCARS panels on the wall are barely altered , so this could be the first LCARS appearance . They also appear in just below the warp core , but they do not appear in the 23rd century portion of . According to a " Next Generation " episode text commentary by Michael and Denise Okuda , the LCARS displays were rarely actual computer simulations ; one such example was the computer screen used by Romulan Commander Sela to monitor the Federation fleet during her attempt to smuggle weapons and supplies to Lursa and B ' Etor during the Klingon civil war in the episode . This was due , according to the Okudas , to both the high cost and primitive state of computer graphics in the late 1980s and early 1990s . Therefore , most LCARS displays were , in fact , plastic panels with spinning light devices behind them to give the impression that the information on the " displays " was changing . In the first two seasons of " The Next Generation " , large black rectangles are clearly visible on the LCARS displays on the bridge ( and sometimes in main engineering ) . This was a result of the studio lights reflecting off the displays , which director of photography Edward R . Brown tried to solve by sticking cardboard onto them . When Brown was replaced by Marvin V . Rush for the third season , a number of changes in filming ( including better film stock and a smaller number of lights ) allowed the LCARS displays to be seen properly . Apocrypha . The LCARS layout has been used in several computer games and applications such as the CD - ROM version of the " Star Trek Encyclopedia " , as well as the and CD - ROM Companions . The LCARS layout is also used on the " Star Trek " PADD app for the Apple iPad .