A "listed building" is a special type of building in the United Kingdom that is considered to be very important and historically significant. This means that the building has been given a special status by the government to protect it from being changed or destroyed.
Just like how your parents might have some special family heirlooms that they don't want anyone to touch or break, the government thinks that some buildings are so important that they need to be kept just the way they are.
If a building is "listed" it means that it is on a special register that the government keeps. There are three different levels of listing: Grade I, Grade II*, and Grade II. Grade I is the most important, followed by Grade II* and then Grade II.
If a building is listed, this means that the owner of the building has to follow special rules if they want to make any changes to it. They have to get permission, called "listed building consent," from their local government or council. This is because the government wants to make sure that any changes that are made to the building won't harm its special historical significance.
For example, if someone wants to add a new door or window, or paint the building a different color, they have to get permission first. If they don't get permission, they could get into trouble with the government.
Listed buildings can be all sorts of different types, like houses, churches, shops, and even castles! They are all special because of their history and the stories they tell about the past.