Categorize parameters with the URL Parameters page

You can use the URL Parameterstool to indicate the purpose of the parameters you use on your site to Google. For example, if you are the owner of a global shopping site, you might tell Google that you use the country parameter to distinguish between pages dedicated to consumers in different countries. Then you can set preferences for Google might crawl the URLs that contain those parameters. The preferences that you set can encourage Google to crawl the preferred version of your URL or simply prevent Google from crawling duplicate content on your site.
In general, URL parameters fall into one of two categories:

• active URL parameters -- parameters that can change page content
• passive URL parameters -- parameters that have no affect on how content appears to the user

Active parameters

Active parameters indicate differences between an original page and a page that contains largely the same content but has been slightly altered by some function. This parameter type can show that a page has been affected in the following ways:

• Sorts (for example, sort=price_ascending): Changes the order in which content is presented.
• Narrows (for example, t-shirt_size=XS): Filters the content on the page.
• Specifies (for example, store=women): Determines the set of content displayed on a page.
• Translates (for example, lang=fr): Displays a translated version of the content.
• Paginates (for example, page=2): Displays a specific page of a long listing or article. Note that you can also indicate paginated content directly.
• Other: Changes content in ways other than those described above.

Some examples of active parameters include: brand, gender, country, sortorder.

Passive parameters

[Why would I want this parameter?] Passive URL parameters are often used to track visits and referrers, but have no affect on the actual content of the page. For example, the following URLs all point to the exact same content:

• http://www.example.com/products/women/dresses?sessionid=12345
• http://www.example.com/products/women/dresses?sessionid=34567
• http://www.example.com/products/women/dresses?sessionid=34567&source=google.com

Some examples of passive parameters include: sessionid, affiliateid.

Tell Google how to handle a URL parameter

1. On the Dashboard, under Crawl, click URL Parameters.
2. Click the Edit button next to the parameter you want to define for Google. If the parameter isn’t listed, you can click Add parameter to create a new one. Note that this tool is case sensitive, so be sure to type your parameter exactly as it appears in your URL.
3. Set your parameter as either active or passive (e.g. changes content displayed to the user or has not impact):
4. For passive: Select No... in the Does this parameter change... list, and then click Save.
5. For active: Click Yes: Changes, reorders, or narrows page content, and then choose one of the options that appears to indicate how you want Google to crawl URLs that contain this parameter. The table below describes the choices.

Parameter	Description	Purpose
Let Googlebot decide	Select if you're unsure of a parameter's behavior, or if the parameter behavior changes for different parts of the site. Googlebot can analyze your site to determine how best to handle the parameter.	This setting is a good general option.
Every URL	Google uses the value of this parameter to compare your URLs and determine if they are unique. For example, after you implement this type of setting for URLs containing the productid parameter, Google automatically considers the URL http://ww.example.com/dresses/real.htm?productid=1202938 to be entirely different from http://www.example.com/dresses/real.htm?productid=5853729 because each URL has a different productid parameter value.	Use this setting to tell Google that URLs with unique values of a specific parameter do not contain duplicated content. Before you select this option for a parameter, be sure that this parameter really does affect or change your page content, or Googlebot might unnecessarily crawl duplicate content on your site.
Only URLs with specified value	Google crawls only URLs where the value of this parameter matches this specified value. URLs with a different parameter value won’t be crawled. This is particularly useful if your site uses the parameter value to change the order in which otherwise identical content is displayed. For example, http://www.example.com/dresses/real.htm?sort=price_high contains the same content as http://www.example.com/dresses/real.htm?sort=price_low. You could use this setting to tell Googlebot to crawl only those URLs where sort=price_low to avoid crawling the duplicate content.	Use this setting to tell Google to crawl only URLs where your URL parameter is set to a value that you specify.
No URLs	Google won't crawl any URLs containing the parameter you entered. For example, you can tell Google not to crawl URLs with parameters such as pricefrom and priceto (like http://www.examples.com/search?category=shoe&brand=nike&color=red&size=5&pricefrom=10&priceto=1000) to prevent unnecessary crawling of duplicated content already available from http://www.examples.com/search?category=shoe&brand=nike&color=red&size=5.	Use this option to tell Google not to crawl any URLs with a specific parameter.

Choose a canonical URL

If your site publishes content that can be reached via multiple URLs, you can choose a representative URL to appear in Google Search results by specifying a canonical (preferred) version of the URL. You can do this with the URL Parameters tool, or you can add the rel="canonical" element to the HTML source of your preferred URL.
Note that to use rel="canonical", you'll need to be able to edit your pages' source code. Learn more about how to use canonical URLs.