Could somebody tell me when to use 'fewer' and 'less'?

Students often don’t know when to use less and when to use fewer in a sentence. Here are how to get them right.

Use fewer if you’re referring to people or things in the plural (e.g. houses, dogs, students, children). For example:

• People these days are buying fewer books.
• Fewer students are opting to study science-related subjects.
• Fewer than thirty children each year develop obesity.

Use less when you’re referring to something that can’t be counted (non countable) or doesn’t have a plural form (e.g. money, air, time, music, rain). For example:

• It’s a better job but they pay you less money.
• People want to spend less time in traffic jams.
• Ironically, when I’m on tour, I listen to less music.

Less is also used with numbers when they are on their own and with expressions of measurement or time, e.g.:

• Their marriage lasted less than two years.
• Ramayana is less than three miles away from Unigraha.