The advantages of External Style sheets are:
- The style of several documents can be controlled from site by using them.
- Multiple HTML elements can have many documents, where classes can be created.
- To group styles in complex situations, selector and grouping methods are used.
Demerits of external css are as follows:
- Extra download is needed to import documents having style information.
- To render the document, the external style sheet should be loaded.
- Not practical for small style definitions.