Earlier, WordPress.com used only categories and no tags. A tag is a new breed of search engine optimization i.e. SEO. Tags are fundamentally keywords for each page or article created by us. It is a non-hierarchical keyword or term assigned to a piece of information such as an internet bookmark, digital image, or computer file. This type of metadata helps depict an item and facilitates it to be found again by browsing or searching. Tags are chosen easily and personally by the item’s creator or by its viewer, depending on the system. Tags are “free-form” words means there is no formal restriction on tags we attach.
Long tag lists should be generally avoided. Tag pages are somewhat like category pages. We can assign related posts the same tag, and then all those posts appear on the same tag page. During the design stages of the site, make a list on a piece of paper of all the tags we want to use on our site. These will be the most important keywords for the niche, but they should be keywords that are different to the categories which we have setup for the site. Tags can be considered as additional pages that WordPress will create offering us a secondary way of filing our posts.
Although, usage of tags made broad grouping of post topics possible yet to describe a post in more specific terms, more categories are needed. A category is an exclusively defined division in a system of classification. A system of classification here refers to a highly structured, possibly hierarchical system. For example, to borrow from the classification system for living things, we have a tree like “Animals -> Vertebrates -> Mammals -> Horses”. Any of these terms can be considered to be a category, and they fall into a strict structure.
The basic difference between categories and tags is that categories are structured and tags are unstructured. Categories organize, hierarchically. Tags need not. Tags provide meta-information, Categories need not. Tags cross-connect, Categories do not. <–>