Acquired from the internet hive mind
That/Which
Grammar geeks go crazy over certain things – too/to/two, that/which usage, your/you’re, there/their/they’re, the Oxford Comma. I think by now you know where I fall on the grammar geek spectrum. So now I am going to geek.
OMG, Melissa McArthur made the most incredible post about That and Which. “That? Which? Wha…?“
She, my hero, even gave a perfect summing up.
So here’s your easy to remember rule: If it can be taken out of the sentence, use which and a comma. If not, use that.
“That” restricts, “which” is non-restrictive.
Go forth and read the post in all of its amazing awesomesauceness here: http://www.magicalwords.net/really-i-mean-it/that-which-what/
Truly, if you ever had ANY questions about how “that” and “which” work, read this post. Be still my beating heart!