A category is used to categorize the different posts. A post can have zero or more categories assigned at any time and you can add and remove categories when you create a post or afterwards when you edit it.
Create new category
There are two places a new category can be created. One is when you edit or create a new post and the other is on the category page in the admin section. The two ways work exactly the same behind the scenes.
Edit an existing category
In the left column of the category table on the admin page, you can click the Edit link. This will display a textbox with the name of the category you want to edit. After you have edited the category, click the Update link to save the change. The category widget
at the front of the blog automatically detects the change and adjusts accordingly.
The category admin page allows you to delete the categories you no longer want. If one or more posts are associated with a category you want to delete, you can still delete the category. The category will be removed from the associated posts, but the associated
posts will not be removed or altered in any other way.