2021 ISSUE 01: Survival
If something is countless, use LESS.
Example: After climbing the stairs, I had less energy.
Will cities of the future have less/fewer pollution than our cities today?
Is your noun abstract? It is probably uncountable.
E.g. work, food, interest, love, beauty, representation
If something is countable, use FEWER.
Example: There are fewer stairs to climb here.
Will cities of the future have less/fewer cars than our cities today?
Can your noun by made into a plural form? It is probably countable.
E.g. children, workouts, pairs of shoes, buildings
Exceptions: Although money, distance, time and weight can be counted in their respective units, we use “less” instead of “fewer”.