When do we use “less” and when do we use “lesser”?
This is a good question. I had to think twice about it.
When you are comparing something, use ‘less’. Ex: It costs less than that. You can also use it for comparison implicitly. Ex: I eat less sugar.
‘Lesser’ on the other hand is generally used to mean ‘inferior’ as in “Which is the lesser evil?”, “There is no such a thing as a lesser man” and “Many lesser poets have won greater awards”.