What are the general areas of usability?

Web usability is an system in making web sites easy to use for the user, therefore not requiring the user to undergo any training.

1. To show the info to the user in a clear way.
2. To lend the correct choice to the user, in an obvious way.
3. To rid any problems regarding the consequences of an action e.g. clicking on delete or remove etc.
4. Put the most important info/logo or most used thing in the right place on a web page.