Examples include:
* Textbooks: They synthesize information from many primary sources to provide a comprehensive overview of a topic.
* Biographies: Written about a person, often relying on letters, diaries, and other primary sources from the subject's life, or interviews with people who knew the subject.
* Journal articles (that analyze other studies): These may analyze data from other researchers' studies (which are primary sources themselves).
* Literary criticism: Essays and books that analyze literary works (the works themselves being primary sources).
* Historical analyses: Books and articles that interpret historical events based on primary source documents like letters, diaries, and official records.
* Reviews: Of books, films, or performances.
The key distinction is that secondary sources *don't directly witness* the event or create the material being discussed. They offer a perspective on something that already exists.