They might end with "etc."

LISTS

When you jot down items one after another, this is what you’re making.

The clue plays on how "etc." (short for et cetera) often appears at the end of a list to show there are more items not mentioned. Since lists are the only things that commonly finish with "etc.," the answer points directly to them. It’s a straightforward definition with a hint of wordplay—no tricks, just observing where "etc." naturally fits.