“Fewer” or “Less”?

FEWER should be used when one can count the items/subjects in question. It is usually used with a following “THAN”.

For example:

1) Today I had fewer than ten phone calls.
2) Fewer awards than advertised were distributed at the Honors Ceremony.

LESS is used for items/subjects that cannot be measured.

For example:

1) You should work less to be healthy.
2) Since we had less snowfall this year, we decided not buy that snowblower.