Notes on English usage - less or fewer?
Supermarkets are fond of displaying a sign over their express queue that reads "6 items or less", although some have now realised that it should be "6 items or fewer". So what's the difference?
When deciding which to use, ask yourself whether the thing or things under discussion are counted or measured.
If you are asking the assistant at the deli counter to give you a piece of cheese that is smaller than the piece she has just offered you, you should ask for less cheese, because this is something that is measured - by weight in this instance. It would make no sense to say "please give me fewer cheese".
However, if she has given you too many olives, you would say "please give me fewer olives", because olives are things you can count.
Be careful when you are dealing with collective nouns, such as "people". You can count people, so it is correct to say "there are fewer people in France than in India" and wrong to say "there are less people".
The golden rule here is - Measure Less, Count Fewer. If you can remember the line from Coleridge's "Kubla Khan" that goes "Through caverns measureless to man", you won't go far wrong!