Notes on capitalization and stemming
Google searches are not case sensitive. All letters, regardless of how you enter them, are understood as lower case. For example, searches for george washington, George Washington, and George washington all return the same results.
To provide the most accurate results, Google does not use "stemming" (key matching for partial-words) or support "wildcard" searches. Rather, Google searches for exactly the words entered into the search box. For example, searching for airlin or airlin* will not yield "airline" or "airlines". If in doubt, try both forms, for example: airline and airlines.
The basic search
To enter a query, type in a few descriptive words and press the enter/return key, click the magnifying glass, or click the search button for a list of relevant results.
Google uses sophisticated text-matching techniques to find pages that are both important and relevant to your search. For instance, Google analyzes not only the candidate page, but also pages linking to it in order to determine the value of the candidate page for your search. Google also prefers pages in which your query terms are near each other (for example, given the query information technology, Google will boost results containing the phrase "information technology" over those containing "information driven by technology").
Note: Encrypted, viewable PDF documents are converted to HTML for indexing; however, the HTML is not displayed.
Automatic "AND" queries
By default, Google returns only those pages that include all entered search terms. There is no need to include "and" between terms.
Google supports the logical "OR" operator. To retrieve pages that include either word A or word B, use an uppercase "OR" between terms.
You can exclude a word from your search by putting a minus sign ("-") immediately in front of the term you want to exclude. Make sure you include a space before the minus sign.
You can search for phrases by adding quotation marks. When searching for phrases, words enclosed in double quotes ("like this") appear together in all returned documents. Phrase searches using quotation marks are useful when searching for famous sayings or specific names.
Additionally, certain characters serve as phrase connectors. Phrase connectors work like quotation marks and join your search words in the same way
Google recognizes hyphens, slashes, periods, equal signs, and apostrophes as phrase connectors.
Google Custom Search supports several advanced operators, which are query words with special functions. A list of the advanced operators with explanations are provided below.
If you start a query with filetype:, the search is restricted to results with the specified file extension. For example, filetype:PDF returns only files with the .pdf extension. A list of file types searchable by Google can be found here.
Note: There can be no space between filetype: and the file type in the query.
Note: Do not include the leading period (".") of a file type when using this operator (i.e., .pdf files use pdf, .ppt files use ppt, etc.).
The search engine keeps the text of the many documents it crawls available in a backed-up format known as "cache." A cached version of a web page can be retrieved if the original page is unavailable (for example, the page's server is down). The cached page appears exactly as it looked when the crawler last crawled it and includes a message (at the top of the page) to indicate that it's a cached version of the page.
The query cache: shows the cached version of the web page. For instance, cache:www.google.com shows the cached page of Google's homepage.
Note: There can be no space between cache: and the web page URL in the query.
If you include other words in the query, those words will be highlighted within the cached document. For instance, cache:www.google.com press releases shows the cached content with the words "press" and "releases" highlighted.
The query info: returns available information for that particular URL. For instance, info:google.com returns a list of information available about google.com.
Note: There can be no space between the info: and the web page URL.
If you start a query with allintitle:, the results are restricted to documents with all of the query words in the document's HTML title. For example, allintitle: google search only returns documents that have both "google" and "search" in the HTML title.
If you include intitle: in your query, the search is restricted to results with documents containing that word in the HTML title. For example, intitle:google search returns documents that mention the word "google" in their HTML title, and mention the word "search" anywhere in the document either in the title or anywhere else in the document.
Note: There can be no space between the intitle: and the following word.
Putting intitle: in front of every word in your query is equivalent to putting allintitle: at the front of your query. For example, intitle:google intitle:search is the same as allintitle: google search.
If you start a query with allinurl:, the search is restricted to results with all of the query words in the URL. For example, allinurl: google search returns only documents that have both "google" and "search" in the URL.
Note: allinurl: works on words, not URL components. In particular, it ignores punctuation. Thus, allinurl: foo/bar restricts the results to page with the words "foo" and "bar" in the URL, but doesn't require that they be separated by a slash within that URL, that they be adjacent, or that they be in that particular word order. There is currently no way to enforce these constraints.
If you include inurl: in your query, the results are restricted to documents containing that word in the URL. For example, inurl:google search returns documents that mention the word "google" in their URL and mention the word "search" anywhere in the document either in the URL or anywhere else in the document.
Note: There can be no space between the inurl: and the following word.
Note: inurl: works on words, not URL components. In particular, it ignores punctuation. Thus, in the query google inurl:foo/bar, the inurl: operator affects only the word "foo," which is the single word following the inurl: operator, and does not affect the word "bar." The query google inurl:foo inurl:bar can be used to require both "foo" and "bar" to be in the URL.
Putting inurl: in front of every word in your query is equivalent to putting allinurl: at the front of your query. For example, inurl:google inurl:search is the same as allinurl: google search.