Good question
- Fewer refers to NUMBER and is used with PLURAL nouns.
- Less refers to DEGREE or AMOUNT and is used with SINGULAR nouns.
Ex: If the organizers had put forth LESS effort (a smaller degree), FEWER people (a smaller number) would have attended the HIV conference.
- The expression less than (instead of fewer than) precedes plural noun referring to periods of time, amounts of money, number, and quantities.
- In other words, less than is used before a NUMBER or AMOUNT to say that the actual number or amount is smaller than this.
Ex: This milk contains less than 20% fat (an amount of fat)
It was less than 2 years ago (a period of time)
