Typical writing mistakes
While it’s true that no writer will ever be perfect, writes Beata Santora at Quick and Dirty Tips, it’s also true that we can continually hone our skills.
She offers a look at seven of the most common writing blunders even good writers make, including Which vs. That.
The words "which" and "that" are not interchangeable. Both begin clauses, but "which" clauses are unnecessary to the meaning of a sentence (and thus set off by commas) and "that" clauses are essential.