Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
Category is regular. It follows the -ies Conversion rule.
Use plural verbs: "The categories are ready" (not "is ready").
Yes. The plural categories is standard across all English variants.
The word category follows the standard English pluralization rule. When forming the plural, category becomes categories. This follows the -ies Conversion pattern, which is one of the most common plural rules in English.
Understanding why category becomes categories helps with spelling and pronunciation. Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
When using categories in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The categories are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.