You can search for lots of stuff in various places throughout the game.
A simple 'search' will find hidden and concealed exits, stealthy characters trying to keep out of your sight, and items that may be concealed somewhere. Keep in mind that while doing this searching, you are noticeably searching the location. If you're in a room, you may be checking behind things for hidden exits, looking behind curtains for hidden people, checking the shadows or even the cupboards, depending on what you end up finding. You and other characters should RP this minutiae.
If you're in a location that is a library of sorts, searching may uncover a book, depending on the situation.
The command 'search here for tracks' will also allow skilled characters to discover tracks and trails while exploring areas of wilderness. *Last Updated: 06/17/18 by Fengshui*