Less and fewer
- I have less money than you.
- He was less hurt than frightened.
- Tom is less clever than his brother.
Fewer is the comparative of few. It is used before plural nouns.
- Fewer people live to be hundred.
In an informal style, less is quite common before plural nouns. Some people consider this incorrect.
- I have got less problems than I used to have. (Less formal than I have got fewer problems than I used to have.)
- I would like to spend less of my time travelling. (NOT --- less my time traveling.)
- I want less of this and more of that. (NOT I want less this ---)
Before nouns without determiners, of is not used.
- If you want to lose weight, eat less food. (NOT --- less of food.)
- Fewer people live to be hundred. (NOT Fewer of people ---)
Lesser means ‘not so much’. It is used in a few expressions.
a lesser-known writer
the lesser of two evils.
Search the Dictionary of Practical English Usage