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Summarization is one of the most immediately useful applications of LLMs, allowing you to rapidly distill the key information from large volumes of text. However, moving beyond basic summarization requires a strategic approach. By mastering a few key techniques, you can transform the LLM from a simple text-shrinker into a sophisticated analysis tool.

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The Spectrum of Summarization

Summarization isn’t a single task; it’s a spectrum. The right technique depends on your goal.
  • Extractive Summarization: This is the simplest form, where the model identifies and pulls out the most important sentences from the original text. It’s fast and factual, but can sometimes feel disjointed.
  • Abstractive Summarization: This is where LLMs truly shine. The model reads and understands the source text and then generates a new summary in its own words. This allows for more fluent, human-readable output and can even simplify complex topics.
By default, most LLMs will perform abstractive summarization, but you can guide them toward a more extractive style if needed.

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From Basic to Advanced Summarization: A Case Study

Let’s explore how to add layers of control to a summarization prompt. Basic Prompt: 
Summarize this article:

[Article Text]
This is a zero-shot prompt that gives the model full control over the length, focus, and style. Prompt with Length Constraint: 
Summarize this article in no more than 100 words:

[Article Text]
Better. We’ve added a crucial constraint to control the output size. Prompt with Format and Focus Constraints: 
Summarize this article in three bullet points. Focus specifically on the financial and market-related outcomes.

[Article Text]
Now we’re getting powerful. We’ve dictated the format (bullet points) and told the model what specific information we care about, instructing it to ignore other aspects of the article. Advanced Prompt with Persona and Audience: 
You are a senior financial analyst. Read the following news article and write a summary for a busy CEO. The summary should be a single, dense paragraph, starting with a clear "Bottom Line" statement. Focus exclusively on the strategic implications for our company and the market at large. Ignore any public relations or human-interest angles.

[Article Text]
This is a professional-grade prompt. It assigns a persona, defines a specific audience (a busy CEO), dictates a highly specific format (“Bottom Line” statement), and provides both positive and negative constraints on the focus.

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A Toolkit of Summarization Techniques

Keep these techniques in your back pocket to create the perfect summary for any situation.
  • Chain of Thought Summarization: Ask the model to first identify the key points, and then summarize those points. This can improve the quality of the final summary.
    • First, pull out the top 5 most important arguments from this text. Then, write a one-paragraph summary based only on those five arguments.
  • Multi-Perspective Summarization: Ask for summaries from different points of view.
    • Summarize the attached meeting transcript from the perspective of the marketing team, and then summarize it again from the perspective of the engineering team.
  • Interactive Summarization: Don’t just take the first output. Ask follow-up questions to dive deeper.
    • That's a good summary. Can you elaborate on the second bullet point?
By moving beyond basic requests and applying these more advanced techniques, you can use LLMs to create highly tailored, insightful summaries that save you time and improve your understanding.