Most singular nouns are made plural by simply putting an -s at the end. There are many different rules regarding pluralization depending on what letter a noun ends in. Irregular nouns do not follow plural noun rules, so they must be memorized or looked up in the dictionary.
Plural Noun Rules
There are many plural noun rules, and because we use nouns so frequently when writing, it’s important to know all of them! The correct spelling usually depends on what letter the singular noun ends in.