What are the advantages and disadvantages of External Style Sheets?

The advantages of External Style Sheets are:

- Using them, the styles of multiple documents can be controlled from one file.
- Classes can be created for use on multiple HTML element types in many documents.
- In complex situations, selector and grouping methods can be used to apply styles.

The disadvantages of External Style Sheets are:

- In order to import style information for each document, an extra download is needed.
- Until the external style sheet is loaded, it may not be possible to render the document.
- For small number of style definitions, it is not viable.