It is common for them to cover topics such as real estate and automobiles on behalf of the paper's frequent advertisers.
Some are published if it's too expensive to revise the main work, such as the first edition of the Oxford English Dictionary.
It can also be used as a companion for up-to-date books, focusing in a specific theme or area, such as Guinness World Records: Gamer's Edition.
They are sold separately and typically cover a specific topic, such as the Times Literary Supplement and the Times Educational Supplement Supplements found on some DVDs, HD DVDs, and Blu-rays are more commonly known as special features, bonus features, or bonus material.
Such supplements can have guest editors,[2] are often not peer-reviewed to the same standard as the journal itself, and are more likely to use promotional language.