can refer to a small careless mistake in any area, not necessarily typing
用法筆記
Shortened form of 'typographical error'. Common in everyday conversation and email; in formal or academic writing, the full phrase 'typographical error' may be preferred.
常見錯誤
I made a typo in my grammar.
I made a grammatical mistake in my sentence.
a typo is a mechanical typing error (wrong letter), not an error in language rules.