A white and blue missing poster is a flyer used to spread the word about a missing person. In this case, it is for a grandfather who has gone missing. The poster typically includes a recent photo of the person, along with their name, age, description, and any identifying features. It may also provide contact information for those who have any information on their whereabouts. Missing person posters are an important tool in raising awareness and helping to locate missing individuals. It is important to act quickly when someone goes missing, as time is of the essence in these situations.