The rule about when to use "between" and when to use "among" seems straightforward, until you look more closely. Then it's not straightforward at all.
Our listener Lowell Boileau wanted to know what we think about this rule:
"My understanding is that 'between' is for 'between two parties' and 'among' is for 'among three or more parties.' Yet I hear and read 'between' frequently used in reference to three or more."
Many of us grew up with this exact same rule, but Lowell is right. Not everyone follows it.