AI writing tools produce fluent text in seconds, and it is often hard to say whether an essay, an assignment or an article was written by a person or by a language model. There is no single, definitive sign, but there are features that often show up in AI-generated text and sensible ways to check a suspicion without accusing anyone unfairly.
Common signs of AI-written text
- A uniform style from start to finish. Sentences of similar length, the same rhythm in every paragraph and no shifts in tone. People tend to mix short and long sentences, change pace when a topic excites them and leave small irregularities behind.
- Generic phrasing. Expressions such as “it is important to note”, “in today’s fast-paced world” or “plays a crucial role” appear often and say little. The text talks about the topic without getting to anything specific.
- No personal detail. There are no lived examples, no risky opinions, no references to the class discussion, the assigned reading or the writer’s own experience. Anyone could have written it about any course.
- Invented or inaccurate sources. Language models can cite books, articles, authors, laws or figures that do not exist, or attribute a real idea to the wrong person. This is one of the most useful signs, because it can be checked.
- Repetitive structure. An introduction that restates the question, three or four sections with the same shape, lists with the same number of items and a conclusion that sums everything up with “in conclusion” or “overall”.
- Excessive balance. The text presents “both sides” of everything and avoids taking a position, even when the task asked for an opinion.
How to check a suspicion
The signs above raise a question. To reach a reasonable answer, combine several kinds of checks:
- Compare it with the author’s other writing. In-class essays, exams, messages and earlier assignments show a person’s vocabulary, habitual mistakes and way of arguing. A sudden change in style deserves attention, but it can have other explanations, such as careful editing or help from a friend.
- Ask about the content. Ask the author to explain an idea from the text in their own words, to say why they chose a particular example or where a piece of information came from. People who wrote the text can usually answer; people who only copied it often struggle.
- Check the sources. Look up the books, articles and data that are cited. A reference that does not exist, or does not say what the text claims, is a concrete problem no matter who wrote the text.
- Use a detector as one more signal. The AI detector below this guide estimates how likely the text is to have been generated by AI, marks fragments as likely AI, suspicious or human with a confidence value and gives an overall verdict, which you can save as a PDF report. It helps you decide where to look more closely, but it can also be wrong.
Why signs alone are not proof
Every one of these signs also appears in text written by people. Students are taught to write introductions that restate the question and conclusions that sum everything up. Technical writing, reports and summaries are impersonal by nature. People writing in a second language tend to use simpler, more predictable sentences. A very careful writer can produce clean, uniform text with no help at all.
At the same time, text generated by AI and then edited by a person can lose almost all of these signs. That is why no single feature, and not even a detector result, can tell you with certainty who wrote a text. What you have is a set of indications that needs to be weighed in context.
How to act responsibly
If you are a teacher, an editor or a reviewer, treat a suspicion as a question, not an accusation. Gather the evidence, listen to the author and give them the chance to show how the text was made: drafts, notes, version history. If you are the author and worry about being misjudged, keep that evidence of your writing process and be ready to explain your choices.
It is also worth remembering that using AI is not always forbidden. Many institutions allow certain uses as long as they are declared. The most useful question is usually not only “was this written by AI?” but “does this text follow the agreed rules and show what the author actually knows?”.