Back of the hand - which side is that then?

[No Einstein]

Which side of one's hand does this saying refer to, please? Is it the side the lines or the side with the knuckles. My gues is knuckles, as in "backhand". But I may be wrong.

[pamnez]

The knuckles are on the back of your hand where the joints of the fingers are when you clench your fist.  Like bare knuckle boxing.

[Quizmonster]

The saying: "I know it like the back of my hand" has always intrigued me. If you were shown ten pictures of different hand-backs, including one of your own, would you be able to pick yours out? (I'm assuming, of course, that none of them has any particular distinguishing markings, disfigurations or whatever.)

I'm pretty sure I couldn't, so I've never quite grasped the notion that it's perfectly obvious that one would.

[backofhand19]

I couldn't agree with you more it is an extremely confusing saying. I think we should all work together and change it to "I know it like the palm of my hand"