This article is from the RSC/UKSC Cricket FAQ, by Ganesh with numerous contributions by others.
And what is Round the wicket?
Over the wicket - Bowling arm closer to the stumps
Round the wicket - Bowling arm away from the stumps
Both terms apply equally to both left-arm and right-arm
How to remember which is which?
Do you have a good mnemonic/analogy?
When the ball is delivered over the wicket the hand delivering the
ball is much more above (over) the wicket than when delivering from
the other side, when the hand delivering the ball is more round the
side. I offer this not as a mnemonic but as my understanding of the
actual reason for the terms.