If you aren’t interested in learning how Google creates the index and the database of documents that it accesses when processing a query, skip this description. I adapted the following overview from Chris Sherman and Gary Price’s wonderful description of How Search Engines Work in Chapter 2 of The Invisible Web (CyberAge Books, 2001).
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...read all of: How Google Works

Force Google to include a term by preceding the term with a “+” sign.

To force Google to search for a particular term, put a + sign operator in front of the word in the query. Note that you should not put a space between the + and the word. So, to search for the satirical […]

...read all of: The + Operator

Understanding how Google treats your search terms will help you devise effective queries and revise ineffective ones.
1. All Search Terms Count

Google returns only pages that match all your search terms.

A search for [ compact fold-up bicycle ] finds pages containing the words “compact” and “fold-up” and “bicycle.” Because you don’t need to include the word AND between your […]

...read all of: Interpreting Your Query

The search terms you enter and the order in which you enter them affect both the order and pages that appear in your search results. In the examples below, click on the similar ways of specifying various searches and note how the results differ.
For simplicity sake, this tutorial uses square brackets to denote Google’s search […]

...read all of: Selecting Search Terms