Our table uses the concept of "hard corners" and "soft corners." I was not aware this wasn't a widespread term.

Something like a 5ft doorway or a 90-degree turn in a narrow hallway would be a hard corner that you cannot cut diagonally.

Something like a tree trunk that blocks a square on the grid but might have some space around it would be a soft corner, meaning you could move diagonally around it.

So we rule a bit differently in these situations based on context. We do "free" diagonal movement so that we don't have to do extra math (you can scoff but when you've got a monk with 60' of movement and the map has difficult terrain, it can get fairly complicated), but hearing that we can just do it automatically in roll20 is tempting.

Quote from scatterbraind >>

Our table uses the concept of "hard corners" and "soft corners." I was not aware this wasn't a widespread term.

Something like a 5ft doorway or a 90-degree turn in a narrow hallway would be a hard corner that you cannot cut diagonally.

Something like a tree trunk that blocks a square on the grid but might have some space around it would be a soft corner, meaning you could move diagonally around it.

That sounds like an excellent description of the default rules. My groups use the term "Hard Corner" too (I think it might be from 4e).

This problem, and the ability to apply spells with a radius of effect, are easily remedied by using hex grid instead of square.