That versus which

That versus which is a word choice in grammar that is too-often done incorrectly.

"That" is a restrictive modifier necessary to identify the noun. Examples include:

• The book that I enjoyed the most was A Choice Not an Echo.
• The movie that is most conservative among modern musicals was Grease (1978).

Rarely is there proper usage of "that" immediately after a comma, because the noun needs to be identified before the comma.

"Which" is for a non-restrictive, non-essential description of a noun, and is often preceded by a comma. Examples include:

• The 2024 presidential election, which is the most important in a century, could be decided by only a few swing states.
• The New Testament, which is the greatest collection of books ever written, can be easily read in merely a few months.

See also

• “That” vs. “Which”: When Do You Use Each?