Page Summary

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• Boolean OR search finds documents containing at least one of a series of terms.

• Boolean operators like AND (.), NOT (-), and OR (|) can be used incr andlr parameters to refine search results.

• Parentheses can be used with Boolean operators to control the order of evaluation in search queries.

• You can internationalize queries by specifying interface language and filtering results by language using parameters like "hl" and "lr".

• SafeSearch can be used to filter adult content from search results using the "safe" parameter.

Boolean OR Search

Boolean Operators

You may use Boolean operators in values for the following parameters:

• cr
• lr

Boolean Operator Definitions

Note: You cannot include spaces in parameter values.

Internationalizing Queries and Results Presentation

The Google WebSearch service enables you to search for documents in multiple languages. You can specify the character encoding that should be used to interpret your HTTP request and to encode your response. You can also filter results to only include documents written in certain languages.

The following sections discuss issues related to searching in multiple languages:

• Interface Languages
• Simplified and Traditional Chinese Search

Interface Languages

You can use the "hl" request parameter to identify the language of your graphical interface. The "hl" parameter value may affect search results, especially on international queries when language restriction (using the "lr" parameter) is not explicitly specified. In such cases, the "hl" parameter may promote search results in the same language as the user's input language.

We suggest you explicitly set the "hl" parameter in search results to ensure that Google selects the highest quality search results for each query.

Please see theSupported Interface Languages section for a complete list of valid values for the "hl" parameter.

Simplified and Traditional Chinese Search

Simplified Chinese and Traditional Chinese are two writing variants of the Chinese language. The same concept may be written differently in each variant. Given a query in one of the variants, the Google WebSearch service can return results that include pages in both variants.

To use this feature:

1. Set the "c2coff" request parameter to0
   and
2. Do one of the following:
   • Do not set the "lr" request parameter
     or
   • Set the "lr" request parameter tolr=lang_zh-TW|lang_zh-CN

The following example shows the query parameters you would include in a request for results in both simplified and traditional Chinese. (Note that additional required information, such as the "client", is not included in the example.)

search?hl=zh-CN    &lr=lang_zh-TW|lang_zh-CN    &c2coff=0

Filtering Results

Google WebSearch provides a number of ways to filter your search results:

• Automatic Filtering of Search Results
• Filtering Adult Content with SafeSearch

Automatic Filtering of Search Results

In an effort to provide the best search results possible, Google uses two techniques to automatically filter search results that are generally considered undesirable:

• Duplicate Content—If multiple documents contain the same information, then only the most relevant document of that set is included in your search results.

• Host Crowding—If there are many search results from the same site, Google may not show all the results from that site or may show the results lower in
  the ranking than they otherwise would have been.

We recommend you leave these filters on for typical search requests because the filters significantly enhance the quality of most search results. However, you can bypass these automatic filters by setting the "filter" query parameter to0 in your search request.

Filtering Adult Content with SafeSearch

Many Google customers do not want to display search results for sites that contain adult content. Using our SafeSearch filter, you can screen for search results that contain adult content and eliminate them. Google's filters use proprietary technology to check keywords, phrases and URLs. While no filters are 100 percent accurate, SafeSearch will remove the overwhelming majority of adult content from your search results.

Google strives to keep SafeSearch as current and comprehensive as possible by continually crawling the Web and by incorporating updates from user suggestions.

You can adjust the degree to which Google filters your results for adult content using the "safe" query parameter. The following table explains Google's SafeSearch settings and how those settings will affect your search results:

International Values

• Supported Interface Languages
• Country Collection Values
• Country Codes

Supported Interface Languages

Google supports more than 80 languages. The default interface language is English. The following list identifies all of the interface languages that Google supports.

Country Collection Values

You can use the following values to specify a country filter using the "cr" query parameter:

Country Codes

The following table lists the two-letter country codes that can be used as values of the "gl" parameter: