các is used when the speaker talks about more than one person or thing as a group. Speakers use các to show that a noun is plural and that the members are seen individually but grouped together.
The focus is on a definite group, not on an unspecified amount.
[1] – Các sinh viên đang làm bài tập. The students are doing their homework.
→ The speaker has a specific group of students in mind.
[2] – Các bạn ngồi xuống nhé. Everyone (you all) please sit down.
→ Common in speech to address multiple people.
[3] – Tôi thích các món ăn Việt Nam. I like Vietnamese dishes.
→ The dishes are seen as a category, not just one item.
các vs những
– các: definite, known group – những: more general or descriptive group
[4a] – Các học sinh trong lớp này rất chăm. The students in this class are very hardworking.
[4b] – Những học sinh chăm chỉ thì thường học tốt. Hardworking students usually study well.
các vs no plural marker
– Vietnamese nouns can be plural without any word – các adds clarity or emphasis on the group
[5a] – Trẻ em thích kẹo. Children like candy. (general)
[5b] – Các trẻ em trong làng thích kẹo. The children in the village like candy.
• các comes before the noun.
• Common with people and countable nouns.
• Not usually used with uncountable nouns (e.g. nước, gạo).
• Often sounds more formal or clear than leaving the noun bare.
• các + noun
– Các vấn đề này rất quan trọng. These issues are very important.
• các + classifier + noun (less common)
– Các con chó này rất thông minh. These dogs are very smart.
các helps Vietnamese mark “these people / those things” as a group — clear, specific, and shared in context.