Adding Tags to a post Categorizes that post on your sidebar. Categorizing a post in this way allows visitors to your blog to easily find posts that cover a specific topic.
Tagging a Post is as easy as using the Tags section to check off any previously added Tags that apply and adding any new Tags that seem appropriate via the Add link.
Once you add a Tag it's always available to use for future posts.
Any Tags that are used with a blog post will show up in the Categories section of your blog's sidebar. Clicking on a Tag will display all blog posts associated with that Tag.
If you don't see a Categories section on your sidebar, you can add one by dragging a Categories element to the page.
We recommend you use a certain amount of restraint when creating Tags. If you keep the number of Categories to a minimum (say, less than twenty or so) it'll be easier for visitors to find posts that interest them. Creating a new Tag for almost every post makes the Categories difficult to navigate and significantly less useful for your visitors.