A document is a written, printed or electronic record, such as a book, brochure, magazine, newspaper, or web page. Documents are used in many different fields and disciplines, and they can be very different in terms of content and format. Documents can also be used to communicate information, store data, and provide evidence of ideas and events. Documents can be divided into two main categories: primary documents and secondary documents. Primary documents are original documents created at the time of an event or during a period of history. Examples of primary documents include historical documents, legal documents, medical records, business documents, and personal letters. Secondary documents are documents created after the event or period has passed. Examples of secondary documents include books, magazines, and articles that provide information about the event or period. Secondary documents can also include collections of primary documents, such as archives. Documents can also be classified in terms of their purpose. Informational documents are used to provide information about a topic, such as a book about a certain country or a brochure about a certain product. Persuasive documents are used to convince, influence, or persuade people to take a certain action, such as a political campaign advertisement or a legal brief. Formal documents are those that follow specific rules or conventions, such as a contract or a technical manual. Documents can also be classified based on their format. Printed documents are physical, tangible documents that are printed on paper or other materials, such as books, newspapers, and magazines. Electronic documents are digital documents, such as web pages, PDFs, and emails. Finally, documents can be classified based on their audience. Public documents are those that are intended for a general audience, while private documents are those that are intended for a specific group of people. For example, a book about a certain country is a public document, while a legal contract is a private document.