What the tool actually returns
The tool makes the change visible; the page makes it learnable
The checker does not append a rule to each correction — it returns the corrected text and a change list, each fix shown as old → new. That list is the working material: it tells you exactly what moved, and the pattern behind it is named below. This order beats a textbook for one reason — the mistake being explained is your own, in your own sentence.
In short
Read the list for repeats, not for single fixes.
One correction is a typo. Three of the same kind in one text is a rule you do not know yet, and it is worth five minutes. Write down the repeats, find the pattern for each, and check those constructions yourself before the next send.
- Best for
- ESL emails, essays, cover letters, and any repeated grammar mistake you want to understand.
- Not ideal for
- Legal, medical, or subject-matter review; grading; and writing tasks that need a full pedagogical explanation.
- Fails when
- The source sentence is ambiguous or missing context. Add the surrounding sentence before deciding whether to apply a fix.
See the difference
What you sent, what came back, and the rule behind the change.
Patterns worth separating in the change list
- Subject-verb agreement
- The verb matches the true subject of the sentence, even when another noun sits closer to it.
- Verb form
- The form following an auxiliary such as “will” follows the pattern that auxiliary requires.
- Punctuation
- Commas and apostrophes clarify sentence boundaries and ownership; a change there is usually structural, not cosmetic.
- Word choice
- A grammatically valid word can still be the wrong word for your meaning, so review that pair against what you intended.
Open the full Grammar Checker to test a real sentence.