Meta tags are a type of tag included in your HTML, either in your site header or as attributes in links – effectively descriptors for other tags – that direct web browsers and search engines to parse your site in a particular way. Some of these tags are automatically included with just about any possible way of creating a website. Some of them are more important inclusions to guide Google around your site. Some are old and disused; others are new to Google and are barely supported by other search engines. Because Google is the lord and master of SEO, use them as a guide; these are the tags Google recognizes, and how to use them.
This string is added to the <head> tag of your website. What it does is creates a textual description of the content of the page.
How to use it: The description tag is the description of the page, not the website as a whole. Make sure to create SEO-friendly unique descriptions for each page. This text is extremely important, because it’s what Google uses to generate the text snippet that appears beneath your site in a Google search result. Include relevant keywords in plain language and use it to entice readers to view the page.
The title tag is also added to the <head> of your document, but it does not rest inside the <meta> tags. It isn’t, technically, a meta tag of its own, but it is treated as such. The title is what generates the words that appear in the title bar of your browser. The title is also what appears as the anchor text for a link in the search results.
How to use it: Title tags are incredibly important for SEO for a number of reasons. First, they control the blue anchor text of a Google search result. Second, they provide an easy place to include a keyword and your brand name. Third, they must be unique in order to avoid duplicate content penalties.
Both of these tags, also present in the <head> tag, control how a search engine functions as it crawls your site. They work on a per-page basis. The “robots” name is general and applies to all search engines. The “googlebot” name applies specifically to the Google search engine, if you want it to behave differently than other search engines. Note that this operates in the same way as a robots.txt file, with one difference. Robots.txt operates on a site-wide basis, while the robots meta tag specifies behavior on a per-page basis.
How to use it: The [value] sections listed above are where you can plug in specific values to control the search engine bot behavior. The values Google follows are:
• Noindex – This value specifies that the page should not be indexed. Use it when you don’t want a particular page to show up in the search results.
• Nofollow – This value specifies that links on the page should not be followed. Use it when a link leads to a site you don’t want to pass authority to, or when it leads to a page that is inaccessible to Google, such as one behind a login wall.
• Nosnippet – This value specifies that there should be no textual snippet for this page in the search results.
• Noodp – This value specifies that Google should not use ODP or DMOZ alternate descriptions.
• Noarchive – This value specifies that Google should not create a cached version of the page. You can use an additional value to specify a date to implement the action.
• Noimageindex – This value specifies that images on the page should not appear in search results.
Use a general robots.txt to control behavior across your entire site. Use meta robots tags to control page directives, when they differ from what you want the search crawlers to do across the whole of your site.
As a common example, when a user performs a search in English and finds a series of results for their query in Spanish, Google will often apply their translation software to generate a translated version of the content for consumption by the English searcher. This attribute tells Google not to offer this option.
How to use it: If you have content in a non-English language and you do not want it translated into English for one reason or another, implement this tag. It will not prevent the user manually copying the text and running it through a translator, but it will prevent Google from offering the option by default.
When you create a site and implement Google Webmaster Tools tracking, you are instructed to verify your ownership of the site. To do this, Google requires that you put in some of their tracking code in the meta tags of the homepage. Google provides the code; you put it in this tag.
How to use it: If you’re planning to use Google Webmaster Tools or Google Analytics, you will need to follow this process. Google will generate the code for you, all you need to do it put it into the <head> section in the appropriate location. This tells Google that you are the owner of the site and they will then provide you access to Webmaster Tools and various tracking options.
This tag is used to define the character set and content type of the content on your page. The majority of the time, this is already implemented by whatever software you used to create your site. It’s rare that you will have to change it. Typical character sets include Unicode/UTF-8
How to use it: Allow your software to generate it automatically. Tampering with it is one of the most common errors Google finds in meta data for a site.
Other meta tags exist for various purposes, including the potentially-important geotagging meta tags. Google does not recognize or use these tags, though they may have valid purposes beyond directing the search engine. Meta tags not recognized by Google are ignored, so feel free to use them, unless they create errors that will be parsed improperly.