- Selecting the HTML elements and manipulating them.
- Making AJAX calls in an cross-browser compatible way.
- Processing the AJAX response using the JQuery selectors which include XPath expressions as a subset.
- Traversing the HTML elements, attributes using the Selectors.
To know the full power of what you can do with JQuery watch out these links where JQuery is the core of making these
Spinning 3D Universe
and last but not the least, JQuery comes with full documentation, and tutorials. An interesting visual documentation for JQuery is very handy.