If you want to quote someone or something in your work, and you notice the source material contains a spelling or grammatical error, you use sic to denote the error by placing it right after the mistake. It shows your readers that you didn't just make a typo.
Is it rude to write sic?
There are many contexts where it's appropriate to use [sic], particularly formal writing such as newspaper articles, academic essays, and legal documents. However, it's often inappropriate to use [sic], where it might clutter the text, seem unnecessarily petty, or offend the quoted author.
What is sic and when is it used?
[Sic] signals that a quote appears as originally found, without edits. Sic usually appears in parentheses or brackets, sometimes with the letters in italics.
How is sic used in a sentence?
Sic is usually italicized and always surrounded by brackets to indicate that it was not part of the original. Place [sic] right after the error. Example: She wrote, They made there [sic] beds. Note: The correct sentence should have been, They made their beds.