Why jQuery?

There are many following functionality.
       1. Cross-browser support (IE, Safari, Opera,Chrome,Firefox)
       2. AJAX functions
       3. CSS functions
       4. DOM manipulation
       5. DOM transversal
       6. Attribute manipulation
       7. Event detection and handling
       8. JavaScript animation
       9. Hundreds of plug-ins for pre-built user interfaces, advanced animations, form validation etc.
       10. Expandable functionality using custom plug-ins