In the field of book publishing, a collection or, more precisely, editorial collection (French: collection éditoriale; Spanish: colección editorial; Italian: collana editoriale; Portuguese: coleção de livros, lit. 'collection of books'), is a set of books published by the same publisher, usually written by various authors, each book with its own title, but all grouped under the same collective title. The collective title is the title of the collection, it must be mentioned on each book.
The books that make up an editorial collection can be published in a specific order or not. When each volume in the collection has a serial number, it is called a numbered collection.