A category is used to categorize the different posts. A post can have zero or more categorise assigned at any time and you can add and remove categories when you create a post or after when you edit it.
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(item description)Description
(item description)EditCreate new category
There are two places a new category can be created. One is when you edit or creates a new post and the other is on the category page in the admin section. The two ways does exactly the same thing behind the scenes.
EditEdit 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 notices the change and adjusts accordingly.
EditDelete category
The category admin page allows you to delete the categories you no longer want. In the case where one or more posts are associated with a category you want to delete, you can still delete the category. The associated posts will simple break the association and continue to work as before. In other words, you can delete categories without anything bad happens to the posts.