Nouns

Most nouns form their plural by adding '-s'.
chair, chairs
plate, plates

Nouns which end in '-s', '-ss', '-ch', '-x', and '-z', make their plurals by adding '-es'
mass, masses
match, matches

Nouns which end in a consonant (e.g. m, t, p) + '-y', form their plurals by taking away the '-y' and adding '-ies'
baby, babies
university, universities