A good summary lets someone understand what the author is trying to establish, how the important ideas connect, and what conclusion follows. Before cutting sentences, name the source’s purpose in one line. Is it reporting a finding, explaining a process, arguing for a position, or recording a decision? That sentence becomes the summary’s spine.
What a good summary keeps
Keep the central claim or question, the minimum context needed to understand it, and the main reasons, findings, or steps that support it. Preserve facts that change the meaning: key names, dates, quantities, comparisons, definitions, and outcomes. Keep qualifications too. Words such as may, in this sample, or under these conditions can be as important as the headline result. If the source distinguishes evidence from opinion, or correlation from causation, the summary should maintain that distinction. For a report, include its conclusion and any clear action item. For research, keep the method when it affects how the findings should be interpreted.
What to cut
Cut repetition, decorative openings, long transitions, side anecdotes, duplicate examples, promotional language, and background the intended reader already knows. Quotes usually become paraphrases unless the exact wording is itself important. One strong example can stand in for several similar ones. Details that are interesting but do not support the central purpose belong outside a short summary. Do not cut counterarguments, limitations, exceptions, or uncertainty simply because they make the result less tidy.
Match the format to the job
A TL;DR is useful for triage, while Key Points makes separate takeaways easy to scan. An academic abstract should retain purpose, method, finding, and implication. ELI5 trades jargon for simple language and an analogy, but should not distort the idea. Email and social options adapt the source for an audience; they are not neutral substitutes for the original.
After generating a draft, compare every sentence with the source. Check numbers, names, negatives, cause-and-effect claims, and who said what. Ask whether the summary gives too much weight to a vivid example or drops a decisive caveat. Then tighten it again: merge overlap, replace vague phrases with specific ones, and remove anything that does not help the reader grasp the main point.
A practical test is whether a reader can answer three questions: What is this about? What matters most? What should I understand or do next? If the answer is clear without exaggeration, the summary is doing its job. When accuracy matters, use the summary as a guide back to the source, not as a replacement for it.