Using the robots meta tag

Tuesday, March 06, 2007

Recently, Danny Sullivan brought up good questions about how
search engines handle meta tags.
Here are some answers about how we handle these tags at Google.

Multiple content values

We recommend that you place all content values in one meta tag. This keeps the meta tags easy to
read and reduces the chance for conflicts. For instance:

If the page contains multiple meta tags of the same type, we will aggregate the content values.
For instance, we will interpret

the same way as:

If content values conflict, we will use the most restrictive. So, if the page has these meta tags:

We will obey the noindex value.

Unnecessary content values

By default, Googlebot will index a page and follow links to it. So there’s no need to tag pages
with content values of index or follow.

Directing a robots meta tag specifically at Googlebot

To provide instruction for all search engines, set the meta name to robots. To
provide instruction for only Googlebot, set the meta name to Googlebot. If you want
to provide different instructions for different search engines (for instance, if you want one
search engine to index a page, but not another), it’s best to use a specific meta tag for each
search engine rather than use a generic robots meta tag combined with a specific one. You can find
a list of bots at robotstxt.org.

Casing and spacing

Googlebot understands any combination of lowercase and uppercase. So each of these meta tags is
interpreted in exactly the same way:

If you have multiple content values, you must place a comma between them, but it doesn’t matter if
you also include spaces. So the following meta tags are interpreted the same way:

If you use both a robots.txt file and robots meta tags

If the robots.txt and meta tag instructions for a page conflict, Googlebot follows the most
restrictive. More specifically:

• If you block a page with robots.txt, Googlebot will never crawl the page and will never read any
  meta tags on the page.
• If you allow a page with robots.txt but block it from being indexed using a meta tag, Googlebot
  will access the page, read the meta tag, and subsequently not index it.

Valid meta robots content values

Googlebot interprets the following robots meta tag values:

• noindex: prevents the page from being included in the index.
• nofollow: prevents Googlebot from following any links on the page. (Note that this
  is different from the link-level nofollow attribute, which prevents Googlebot from
  following an individual link.)
• noarchive: prevents a cached copy of this page from being available in the search
  results.
• nosnippet: prevents a description from appearing below the page in the search
  results, as well as prevents caching of the page.
• noodp: blocks the
  Open Directory Project description of
  the page from being used in the description that appears below the page in the search results.
• none: equivalent to noindex, nofollow.

A word about content value none

As defined by
robotstxt.org, the
following direction means noindex, nofollow.

However, some webmasters use this tag to indicate no robots restrictions and inadvertently block
all search engines from their content.