public information system

 what is public information system ?
A system designed to present information to the public or large audience all at the same time.

 Name 2 example ?  
1.  Train stations also need this information.
2. In airports, presenting the arrival and departure information on monitors and electronic boards is essential for the smooth operation of the airport.

 why is it important they are up to date ?

  Because if not people will not know many about other country .