Here's a breakdown:
Include the subtitle if:
* The subtitle significantly clarifies the book's topic or theme: If the subtitle provides essential information that the title alone doesn't, it's beneficial to include it in the summary. For example, "The Lord of the Rings: The Fellowship of the Ring" is more informative than just "The Lord of the Rings."
* You're writing a formal academic summary: In academic contexts, it's often considered good practice to include the complete book title, including the subtitle.
* The subtitle provides a compelling hook: If the subtitle is catchy or intriguing, including it can help draw readers in and pique their interest.
Don't include the subtitle if:
* The subtitle is merely descriptive or repetitive: If the subtitle simply restates information already implied by the title, it's unnecessary to include it.
* You're writing a short, informal summary: For a brief summary, the title alone might suffice.
* The subtitle is overly long or complex: In these cases, including the subtitle can make the summary clunky and difficult to read.
Ultimately, the decision of whether to include the subtitle is up to you and depends on your specific context and goal. Consider the purpose of the summary and the target audience.
Example:
Formal Academic Summary:
* "The Lord of the Rings: The Fellowship of the Ring," by J.R.R. Tolkien, is a fantasy epic that chronicles the journey of a fellowship tasked with destroying the One Ring.
Informal Summary:
* "The Lord of the Rings" is a classic fantasy novel that follows the adventures of a group of hobbits on a quest to destroy the One Ring.