I've seen many people who create a bunch of tags to their post. A tag might be useful when people search on your blog. But, unfortunately, it doesn't impact much on SEO (Search Engine Optimization) part. Sometimes people who tag their post with some keywords just looks like a paragraph. This question was already resolved by Google Webmaster Forums. But still some people concentrate on Tags and categories. It is said that Google doesn't concentrate much on tags and categories. They are just for differentiating each posts.
As most of the bloggers receive more traffic through Google than any other search engines, I have described here by taking Google into the hand.
First of all, instead of adding tags to the post, it will be much better if the post is filed under certain appropriate categories. This also, won't create a much impact on SEO but users will find much easier to ponder though your blog than tagging posts.
There is nothing like advantage or disadvantage if you talk about tags and categories with respect to SEO. They are just to make differentiation with the posts. Google will identify about what you have posted with your article. It is not much essential to make the search engines to know by Tags and categories.
You can spend some time for adding your post into certain appropriate categories but making a list of tags are unnecessary. Google can easily identify the content. When a phrase occurs once, then you have something related to it. When it occurs twice, your SEO is somewhat good. And, thrice, your post is useful related to that phrase. This is what mean, keyword density. Google also calculates how many times, a keyword is found on an article and will relate that article more in that section.
If you are a WordPress blogger and if you use WordPress SEO by Yoast plugin, it will show you how far your focused keyword has a density on your article. A very easy way to calculate.
I don't mean that tags are not useful always. Tags are really helpful when you don't have a category of any word that relates to your article. you might be having only few categories to display it on your homepage navigation or sidebar. Tags might replace this disadvantage on categories. Tags are also useful when someone searches on your blog. When the search keyword matches with the tag you created with any post, then it will show up all the posts tagged under that particular category.
So, what's the conclusion? You might ask. There is no much impact over categories and tags as far SEO is taken into the hand. So, you don't need to concentrate on tags and categories for SEO purposes because Google will find what your post is about by looking at the article and not at your tags or categories. To make your site more friendly and easy accessible to the visitors, you might use categories and tags.
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