Source: A quick and easy guide to meta tags in SEO   Search Engine Watch | 

Meta tags are placed in the <head> section of a HTML document, and are coded in your CMS.

Why do meta tags matter?

Meta tags offer more details about your site to search engines and website visitors who encounter your site in the SERP. Optimizing meta tags will make your website stand out in search results.

Search engines increasingly value positive user experience, which includes finding the best match for the user’s search query. Here’s where meta tags come in – by displaying the useful & concise information searchers need to know about your site right upfront. Some types of meta tag relate to page structure and will ensure that your site is easy to navigate, while others tell search engines which parts of your page are important and which to overlook. Not all meta tags are relevant to SEO. If you want to go deep on this topic, check out: complete guide to meta tags. For now, here are the most important ones to focus on:

Most important meta tags for improving your site SEO:

1. Title tag – Pay attention to your title tags, be clear and descriptive.

The title tag is the title of your page. Hopefully it tells the searcher what your content is about. It’s important to the SERP and it will show up as anchor text and title in social shares. Make your title tag clear, descriptive and less than 55 characters. Adding keywords into the title will enhance SEO but ONLY IF it adds value and doesn’t interrupt the meaning or message of the title. Blend clarity with context and make sure your title makes sense to everyone.

If you’re using a plugin like Yoast SEO in WordPress, allows you to add your title tag in the SEO section and see a preview of how your page will look in search page results. 

Another way to add the title tag is through the site’s HTML, which should look something like this example:

<head>
<title>Example Title</title>
</head>

2. Meta description – Use your meta description wisely and take advantage of the opportunity to provide more details about your content. Make it appealing, concise and relevant.

The meta description is of equal importance to the title tag. If the title tag is the title that appears at the top of a search result, the meta description is the snippet that displays underneath.

The meta description should provide an accurate description of the content of your page. It is usually the element that determines whether users will click on your page, which makes it important to spend time on its optimization.

Previously, the optimum length for meta descriptions was 150-165 characters, but a recent update to the way Google displays search results has resulted in longer snippets being shown on occasion. For more on what this means for SEO and how to adapt, have a read of David Portney’s comprehensive piece, ‘Google’s updated SERP snippet length: What should be your SEO strategy now? 

As with title tags, you can add a meta description via a plugin like Yoast SEO, or code it manually in your website’s HTML, as in this example:

<head>
<meta name="description" content="Here is a precise description of my awesome webpage.">
</head>

3. Robots meta tag – Manage the pages that search engine crawlers access on your site by guiding them through the robots meta tag. Use the robots meta tag to ensure that search crawlers process each page the way you want them to.

The robots meta tag informs search engines which pages on your site should be indexed. This meta tag serves a similar purpose to robots.txt; it is generally used to prevent a search engine from indexing individual pages, while robots.txt will prevent it from indexing a whole site or section of a site.

A robots meta tag which instructs the search engine crawler not to index a page, or follow any links on it, would be written like this:

<meta name="robots" content="noindex, nofollow" />

However, if you want to tell the crawler to index and also follow your page, you would replace the robots tag with this:

<meta name="robots" content="index, follow" />

The robots meta tag is placed in the <head> section of your page, and the result might look like this:

<!DOCTYPE html>
<html><head>
<meta name="robots" content="noindex" />
(…)
</head>
<body>(…)</body>
</html>

If you don’t add a robots meta tag, the default for crawlers is to index and follow your page. 

When to use this meta tag; It might be that you have some pages on your site which are necessary, but quite thin content-wise. You don’t necessarily want them to be indexed in search, but they’re still important to the site, so you can use a noindex tag to prevent them from appearing in the SERPs.

Google also requires links to be nofollowed under certain circumstances. For example, in 2016, it issued a directive to bloggers to nofollow any links that they included as part of a product review, as “these links don’t come about organically”. If you want to nofollow an individual link, you can achieve this by adding rel=”nofollow” to the link HTML.

However, if you wanted to simply nofollow all links on a particular page, you can achieve this with the robots meta tag.

A screenshot of how you can add an Alt-Text in your image optimisation

Image optimization offers an additional opportunity to rank in the search results with your visual content.

Your images should be accessible to both search engines and people. Alt text can ensure both of these things: it provides a text alternative to images which will be displayed if the image doesn’t load, or will be read out by a screenreader; it also tells search engines what that image is meant to represent. You can include keywords in your image alt text, but only if it makes sense to do so – don’t keyword-stuff this tag, as it will only end up harming the user experience for your visitors with accessibility needs.

5. Canonical tag – Use canonical tags to avoid having problems with duplicate content that may affect your rankings.

If you have pages on your site that are almost identical, then you may need to inform search engines which one to prioritize. Or you might have syndicated content  on your site which was republished elsewhere. You can do both of these things without incurring a duplicate content penalty – as long as you use a canonical tag.

Instead of confusing Google and missing your ranking on the SERPs, you are guiding the crawlers as to which URL counts as the “main” one. This places the emphasis on the right URL and prevents the others from cannibalizing your SEO.

A canonical tag can look like this in HTML:

<link rel="canonical" href="http://example.com/" />

6. Header tag (h1, h2, h3, etc.) – Use header tags to help search engines understand your main topic on each page. Use them wisely and find a balance between the reading experience and the SEO value.

Header tags improve user experience by making content easier to read (headlines, subheadlines, subheads, etc.) and they tell search engines what your content is about. The order of your header tags –from h1, which is typically your headline or article title, to h6 which is ranked just higher than paragraph text– tells readers and search engines the importance ranking of each section. Structure them like you would structure an outline in a word document using heirarchy from main point down to lower points. BUT –Less is more here. Use them when they break up the page for the reader showing when new main points are introduced. Adding all 6 levels won’t improve your SEO unless it also improves the reader’s experience.

Example of how header tags can be arranged:

<h1>A quick and easy guide to meta tags in SEO</h1>

<p>Paragraph of content</p>

<p>Another paragraph of content</p>

<h2>Why do meta tags matter?<h2>

<p>Paragraph of content</p>

<h2>Six meta tags to improve the optimization of your site<h2>

<h3>1. Title tag</h3>

It’s usually suggested to use only one h1, while you can use more than one h2 or h3.

Here’s a handy meta tag checklist to use on your site:

  • Check whether all your pages and your content have title tags and meta descriptions
  • Start paying more attention to your headings and how you structure your content
  • Don’t forget to mark up your images with alt text
  • Use robot meta tags to guide search engines on how they should access your content
  • Search for duplicate pages, and use canonical tags to avoid cannibalizing your own content with duplicate or similar content
  • Create a checklist of the steps that you need to repeat when you create new content, and turn meta tags into a part of your routine.

AND…..

The 15 Point SEO Checklist

  1. Title tag starts with keyword phrase
  2. Domain name or filename contains desired keyword phrase
  3. Each content page or product has only one spiderable page – there is no duplicate content on the site and all pages have unique content
  4. Each page has a heading element <h1> containing the targeted keyword phrase
  5. Important site keywords should be linked to other internal pages. For example in this phrase ‘we have additional green lanterns in the gift section’ the keyword ‘green lanterns’ should link to a focused page on this keyword
  6. Your keyword phrase appears in the first sentence
  7. Targeted keyphrases are proximate to each other.For example if your keyword was ‘auto parts’ and this your sentence was ‘find auto parts in our Los Angeles stores’ the phrase ‘Los Angeles stores’ would become part of the secondary keyword phrase.
  8. Main keywords should be highlighted/bold/italics/underlined
  9. Keywords should be towards the beginning of a sentence
  10. Images should be links and use alt text. Alt text is indexed only if the image is hyperlinked.
  11. Meta description tag contains keyword phrase
  12. Title attribute is used in hyperlinks: <a href=”link.html” title=”additional keywords”></a>
  13. Keyword is in the last sentence of the page
  14. Outbound links to major authority site or link to trusted resources, government documents, or third party verification sites. An example of linking out to an authority site would be a CPA business linking to IRS.gov
  15. You can include the keyword in the meta keywords tag, but this has no known impact on website ranking

After you have completed these 15 items for all website pages the next task is off page search engine optimization, which is defined as acquiring backlinks or simply getting people to link to you.