What is "schema" as notes in the nonfiction book, Made to Stick – Why Some Ideas Survive and Others Die?

A schema is a set of facts about a certain individual, event or object. Presenting the name of an object or person or event, causes the individual presented with it to call up the schema or set of facts about it. It’s like a file cabinet or electronic file in the brain. Schemas are important in messaging because they are used to present a new idea to a group or individual by comparing it to an object with a schema that is probably already familiar to them.