Meta Tags are the HTML tags that are inserted inside the head tag and provide meta data(name, keywords, description, author etc.) to the search engines. The visitors cannot see the meta tags i.e. they are not visible but parsable( You can see it through the view source option in most browsers by right clicking on the page). These tags provide the search engine spiders (robots) and the browsers directions and information about the page.
Where to Add meta tags:
Meta tags are added between head( <head>...</head>) tag. You may add the meta tags in all of your web-pages, so not only in the first home page. Ensure that on every page relevant meta tags are added. Add keywords and phrases that are relevant and correspond to the text on that specific page. I know adding meta tags in every page is a tiresome process but soon you'll get good results...
Most Important meta tags (Click To view definition -by metatags.org):
Meta Tags having less Influence (Click To view definition -by metatags.org):
What Influence they have in SEO:
In Search Engine Optimization (SEO) meta tags play a vital role. Especially the meta description is very important due to the fact that this tag is shown as a small text under the search result. This small text combined with a relevant title tag form the text that has to persuade the person that is searching to click on your website. That leads to a much higher CTR (Click Through Rate) and an actual conversion. Eventually it is the CTR and the conversion that make the ranking position of your website.
There are many meta tags and html-tags and obviously they don't all influence the search result. E.g. the html cookie tag doesn't have any influence on your ranking with the search engines but the title of your page, the keywords and the description metatag are very important.
Sites helped me in this article: http://searchenginewatch.com
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