Is that Google takes into account all the meta tags? This is undoubtedly a classic but this time the answer comes directly from Google ... The opportunity to return to each tag to indicate his interest in SEO. Here is a tutorial meta tags as a complete list of these "meta tags" and their impact on SEO.
Although it is not a meta tag, Google confirms that the title tag is used by Google in its ranking algorithm. In short, we must carefully choose what you put into it so that it best describes the page, the most important words at the beginning.
To my knowledge, the meta title does not exist and is not taken into account by search engines:
<meta name="title" content="Un title">
Just a small clarification: the order of meta tags has no impact as long as they are properly filled and located in the header (between <head> and </ head>). Habit often puts the meta charset up, sometimes before the title tag, because it is important to define the character set used.
The meta description tag is taken into account by Google but only for displaying the results. From my tests (officially confirmed by Google in the article), this tag is indeed no impact in terms of positioning. For cons, the Google sometimes takes as a descriptive statement (called the snippet) but it depends on the requests (the meta description is displayed if Google considers it matches the query).
The official explanation from Matt Cutts: "Even though we sometimes use the description meta tag for the snippets we show, we still do not use the description meta tag in our ranking" (source).
Conclusion: it's worth it to write a good message that makes you want the user to click. Integrate marketing, sales and speak directly to her arguments.
It is no longer used by Google, which moreover do not even cites in his article ... If you bothered to fill carefully, let it be used for other engines and directories (that is pretty much what John Mueller said in comments).
In 2009, Google confirmed: "We do not use the keywords meta tag for ranking web" (source). You can watch this video to get to the bottom.
Introduced in September 2012, it is only used for SEO in Google News. One may wonder why Google reintroduced a keywords meta tag then it ignores the meta keywords classic!
For more information, see my file on this news meta keywords.
Although still exite many webmasters who believe the meta revisit-after tag is ignored by Google (as well as other major engines after Google). So you can remove it from your pages ... For information, it is intended to indicate the robots after how long they must return the crawler page. Google knows very well set the robot to adjust its frequency of visits depending on the frequency of updates, if it really haunts you, you can always set this information in the sitemap file.
This tag is taken into account by Google (and other engines). It is used to set restrictions to the robot that comes crawler page. The major search engines also offer webmasters to use a specific tag (googlebot for Google, slurp for Yahoo, etc..), In which case the restrictions concerned apply only specified engine.
Here are the options for the robots meta tag values and their meanings:
noindex: tells the robot should not index the page. This does not mean that the robot will not the crawler: for that you must use the robots.txt file
nofollow: tells the robot should not follow the links in the page. This means that Google will not go crawler pages linked by this page with robots meta tag. Although Google does not say in his article, the engines do not take into account either the links on the page in their algorithm (eg the PageRank).
index: indicates that the robot can index the page. This value is the default, it is totally useless to say.
follow: indicates that the robot can follow the links on the page. This value is the default, it is totally useless to say.
all: this value is equivalent to index, follow. This value is the default, it is totally useless to say.
none: This value is equivalent to noindex, nofollow.
nosnippet: tells the robot should not display description (snippet) in the results page. I fail to see the interest for a webmaster to use this opportunity as this description allows to encourage the user to click on the result (in cases where the description created by the engine can be there is not relevant enough in the eyes of the webmaster).
noarchive: tells the robot should not allow access to the cached version. The link "Cached" on the results page will not be displayed. This is for people who spend their content in an accessible public version to a paid archived version (newspaper sites, for example).
NOODP: tells the robot must not use the data associated with the site by the editors of DMOZ (Open Directory Project ODP) directory. This is useful if the description or title of the site in DMOZ does not correspond well to reality. For more information read the article on the meta NOODP.
unavailable_after: [date] gives the robot the page does not show in the results after the specified date. For more information read the discussion on meta unavailable_after
Yahoo also manages NOYDIR value used as NOODP indicate that the engine does not want data from Yahoo (Yahoo Directory) directory are used. For more information read the article on the meta NOYDIR.
It is possible to combine multiple values within a single meta robots: it suffices to separate the values with commas, for example:
<meta name="robots" content="noodp,noydir">
In the case of syndication, it serves to indicate the URL of the original article. Example:
<meta name="syndication-source" content="http://www.example.com/article-original-pouvant-etre-publie-ailleurs.html">
For more details, see the article on meta tags syndication-source and original-source.
In the event that an article was written from multiple sources (including sources which revealed a scoop), it serves to indicate the URL of the original articles. Example:
<meta name="original-source" content="http://www.example.com/article-original-scoop.html">
For more details, see the article on meta tags syndication-source and original-source.
Google does not use any meta tags geolocation they therefore have no impact on the local ranking on Google (see video source). For information, here despite all their meaning:
geo.position: indicates the latitude and longitude location of the site
geo.placename: indicates the name associated with the site (eg a city) location
geo.region: indicates the identifier of the country and the department (or state for the USA)
ICBM: indicates the latitude and longitude of the location of the site with a different syntax of the meta geo.position
Some believe that Bing takes account of these geo tags but I have not checked yet.
This tag allows you to tell Google that you do not want a link translator is displayed next to the search result. Google may display this link giving access to automatic translation of the page. Google says in his article that this meta tag generally does not affect the position.
About languages, says John Mueller (in blog comments) that Google does not use meta tags to determine what language the page is written (he copes with statistical analyzes of words in the content).
This tag is only for webmasters who use the tools of Google Webmaster Central, it is not essential for good SEO. It is used to prove that one is the webmaster of the site for which the Webmasters Tools account is set.
This tag is used to specify the character set used for the coding of the page.
Originally, this tag is used to reload the page after a specified time in seconds. News sites use it for example to force an update of the display in the browser. Having said all browsers do not necessarily operate in the same way, and the W3C recommends not using it.
In the field of SEO, this tag is sometimes used by some webmasters to redirect the user to another page after a certain time (eg 10 seconds). There has been a lot of abuse with meta refresh configured with a delay of 0 seconds, allowing to hide the contents of the web pages satellite.
If you need to do a permanent redirect, make a server with a 301 redirect instead of a meta refresh redirection with 0 seconds of time (which is not considered by Google as a true 301 redirect).
It is not meta tags but that's very similar. Here is a list (click on links for details):
canonical link: it sets the official URL of a page, to reduce problems with duplicate content
link standout: it allows to define the best articles of the week for Google News in the United States.
I simply reiterate once again that those who still think that SEO plays at optimizing meta tags have several subways late ... There are plenty of other things to work on his website before the meta tags, including the backlink and the creation of original content!
It is noteworthy that Google actually ignores the meta keywords tags and revisit-after, and the meta description does not actually have an impact on the positioning.
Tag title
Although it is not a meta tag, Google confirms that the title tag is used by Google in its ranking algorithm. In short, we must carefully choose what you put into it so that it best describes the page, the most important words at the beginning.
To my knowledge, the meta title does not exist and is not taken into account by search engines:
<meta name="title" content="Un title">
Order of meta tags
Just a small clarification: the order of meta tags has no impact as long as they are properly filled and located in the header (between <head> and </ head>). Habit often puts the meta charset up, sometimes before the title tag, because it is important to define the character set used.
Meta tag description
The meta description tag is taken into account by Google but only for displaying the results. From my tests (officially confirmed by Google in the article), this tag is indeed no impact in terms of positioning. For cons, the Google sometimes takes as a descriptive statement (called the snippet) but it depends on the requests (the meta description is displayed if Google considers it matches the query).
The official explanation from Matt Cutts: "Even though we sometimes use the description meta tag for the snippets we show, we still do not use the description meta tag in our ranking" (source).
Conclusion: it's worth it to write a good message that makes you want the user to click. Integrate marketing, sales and speak directly to her arguments.
Meta keywords tag
It is no longer used by Google, which moreover do not even cites in his article ... If you bothered to fill carefully, let it be used for other engines and directories (that is pretty much what John Mueller said in comments).
In 2009, Google confirmed: "We do not use the keywords meta tag for ranking web" (source). You can watch this video to get to the bottom.
Meta news_keywords
Introduced in September 2012, it is only used for SEO in Google News. One may wonder why Google reintroduced a keywords meta tag then it ignores the meta keywords classic!
For more information, see my file on this news meta keywords.
Meta revisit-after
Although still exite many webmasters who believe the meta revisit-after tag is ignored by Google (as well as other major engines after Google). So you can remove it from your pages ... For information, it is intended to indicate the robots after how long they must return the crawler page. Google knows very well set the robot to adjust its frequency of visits depending on the frequency of updates, if it really haunts you, you can always set this information in the sitemap file.
Meta robots
This tag is taken into account by Google (and other engines). It is used to set restrictions to the robot that comes crawler page. The major search engines also offer webmasters to use a specific tag (googlebot for Google, slurp for Yahoo, etc..), In which case the restrictions concerned apply only specified engine.
Here are the options for the robots meta tag values and their meanings:
noindex: tells the robot should not index the page. This does not mean that the robot will not the crawler: for that you must use the robots.txt file
nofollow: tells the robot should not follow the links in the page. This means that Google will not go crawler pages linked by this page with robots meta tag. Although Google does not say in his article, the engines do not take into account either the links on the page in their algorithm (eg the PageRank).
index: indicates that the robot can index the page. This value is the default, it is totally useless to say.
follow: indicates that the robot can follow the links on the page. This value is the default, it is totally useless to say.
all: this value is equivalent to index, follow. This value is the default, it is totally useless to say.
none: This value is equivalent to noindex, nofollow.
nosnippet: tells the robot should not display description (snippet) in the results page. I fail to see the interest for a webmaster to use this opportunity as this description allows to encourage the user to click on the result (in cases where the description created by the engine can be there is not relevant enough in the eyes of the webmaster).
noarchive: tells the robot should not allow access to the cached version. The link "Cached" on the results page will not be displayed. This is for people who spend their content in an accessible public version to a paid archived version (newspaper sites, for example).
NOODP: tells the robot must not use the data associated with the site by the editors of DMOZ (Open Directory Project ODP) directory. This is useful if the description or title of the site in DMOZ does not correspond well to reality. For more information read the article on the meta NOODP.
unavailable_after: [date] gives the robot the page does not show in the results after the specified date. For more information read the discussion on meta unavailable_after
Yahoo also manages NOYDIR value used as NOODP indicate that the engine does not want data from Yahoo (Yahoo Directory) directory are used. For more information read the article on the meta NOYDIR.
It is possible to combine multiple values within a single meta robots: it suffices to separate the values with commas, for example:
<meta name="robots" content="noodp,noydir">
Syndication-source meta tag
In the case of syndication, it serves to indicate the URL of the original article. Example:
<meta name="syndication-source" content="http://www.example.com/article-original-pouvant-etre-publie-ailleurs.html">
For more details, see the article on meta tags syndication-source and original-source.
Original-source meta tag
In the event that an article was written from multiple sources (including sources which revealed a scoop), it serves to indicate the URL of the original articles. Example:
<meta name="original-source" content="http://www.example.com/article-original-scoop.html">
For more details, see the article on meta tags syndication-source and original-source.
Meta geo.position and geo.region
Google does not use any meta tags geolocation they therefore have no impact on the local ranking on Google (see video source). For information, here despite all their meaning:
geo.position: indicates the latitude and longitude location of the site
geo.placename: indicates the name associated with the site (eg a city) location
geo.region: indicates the identifier of the country and the department (or state for the USA)
ICBM: indicates the latitude and longitude of the location of the site with a different syntax of the meta geo.position
Some believe that Bing takes account of these geo tags but I have not checked yet.
Meta tag google notranslate
This tag allows you to tell Google that you do not want a link translator is displayed next to the search result. Google may display this link giving access to automatic translation of the page. Google says in his article that this meta tag generally does not affect the position.
About languages, says John Mueller (in blog comments) that Google does not use meta tags to determine what language the page is written (he copes with statistical analyzes of words in the content).
Meta verify-v1
This tag is only for webmasters who use the tools of Google Webmaster Central, it is not essential for good SEO. It is used to prove that one is the webmaster of the site for which the Webmasters Tools account is set.
Meta http-equiv charset
This tag is used to specify the character set used for the coding of the page.
Meta http-equiv refresh
Originally, this tag is used to reload the page after a specified time in seconds. News sites use it for example to force an update of the display in the browser. Having said all browsers do not necessarily operate in the same way, and the W3C recommends not using it.
In the field of SEO, this tag is sometimes used by some webmasters to redirect the user to another page after a certain time (eg 10 seconds). There has been a lot of abuse with meta refresh configured with a delay of 0 seconds, allowing to hide the contents of the web pages satellite.
If you need to do a permanent redirect, make a server with a 301 redirect instead of a meta refresh redirection with 0 seconds of time (which is not considered by Google as a true 301 redirect).
<link> Tags in the HTML header
It is not meta tags but that's very similar. Here is a list (click on links for details):
canonical link: it sets the official URL of a page, to reduce problems with duplicate content
link standout: it allows to define the best articles of the week for Google News in the United States.
Conclusion on meta tags
I simply reiterate once again that those who still think that SEO plays at optimizing meta tags have several subways late ... There are plenty of other things to work on his website before the meta tags, including the backlink and the creation of original content!
It is noteworthy that Google actually ignores the meta keywords tags and revisit-after, and the meta description does not actually have an impact on the positioning.
