Semantic HTML là gì? Tại sao quan trọng?

Semantic HTML dùng thẻ có ý nghĩa mô tả nội dung (<article>, <nav>, <header>, <main>, <aside>) thay vì thẻ chung (<div>, <span>).

Quan trọng vì:

1. SEO — search engines hiểu cấu trúc trang tốt hơn.
2. Accessibility — screen readers navigate bằng semantic landmarks.
3. Maintainability — code tự mô tả, đọc hiểu nhanh hơn.
4. Consistency — team dùng cùng conventions

Semantic HTML uses tags that describe the meaning of content (<article>, <nav>, <header>, <main>, <aside>) rather than generic containers (<div>, <span>).

It matters because:

1. SEO — search engines better understand page structure.
2. Accessibility — screen readers navigate using semantic landmarks.
3. Maintainability — self-documenting code is easier to read.
4. Consistency — teams share the same conventions