các

1. Plural markers are optional:
In Vietnamese, you do not need a plural marker for general statements. For example, Tôi thích mèo means "I like cats." You only use các when you want to emphasize plurality or refer to a specific group.

2. How to use it:
Put các before the noun phrase you want to make plural. If the noun requires a classifier, các must go before the classifier, not directly before the noun (e.g., các con mèo = all the cats, never các mèo). However, certain nouns, particularly human roles and professions (like sinh viên, giáo viên, bác sĩ), do not strictly require classifiers, allowing các to attach directly to them. Combining các with a kinship term is the standard way to create plural pronouns (các bạn = you guys, các anh = you/they older males). Note that true personal pronouns use chúng instead (e.g., chúng tôi, chúng nó), not các.

⚠️ Important Warning: Never use các người to mean "you people." In Vietnamese, các người is a highly aggressive and derogatory pronoun. Do not use it unless you intend to be insulting.

3. The "Totality" Rule:
Các is a definite plural marker. This means it refers to every single member of a known group. If you say các sinh viên, you mean "all the students" in that specific context.

4. No numbers allowed:
Never use các with a specific number. Say ba người (three people), not các ba người. If you want to say "all three people", use cả instead: cả ba người. Note that while các cannot be used with numbers, những CAN be used with numbers to mean "as many as" or to express surprise at a large amount (e.g., những ba người).

5. Các vs. Những:
This is a crucial distinction! Use các for the whole group ("all of the"), but use những when you only mean a subset ("some of" or "several").