Wire nuts, likely. The directions on the last box I bought say that twisting is allowed but not required. I would think the reason to twist is to improve the me

Wire nuts, likely. The directions on the last box I bought say that twisting is allowed but not required. I would think the reason to twist is to improve the mechanical connection, not the electrical one. It should make it more resilient to grabbing two wires and pulling in opposite directions. Which shouldn't happen in practice anyway, but, you know. Regardless of how you feel about wire nuts, if you're in the US, your house is probably full of them.