Always try to refine your search:

Searching for the expression air compressor will gather all documents that contain the word air along with any other document that contains the word compressor.
To search for a collection of words, "USE QUOTES"! Typing the expression "air compressor" (with quotes) would get documents that only have that exact phrase in them.

Boolean expressions are permitted:

Each word may be preceded by the standard Boolean operators OR, AND, or NOT.
The default value is OR. Therefore, a typical search for side pipe exhaust would return pages with at least one of the three terms located somewhere within the text.
Typing the phrase AND air AND compressor AND distributors will find only those documents which contain all three search terms. The words need not be grouped together in the document.
Searching for lubrication NOT camshaft will result in a search for all documents containing the word lubrication, but will omit any document that contains the word camshaft.
Alta Vista's + & - notations work too. A search for +air +compressor +distributors will return the same documents as the AND (third) example and lubrication -camshaft is equivalent to the NOT (fourth) example.

Case sensitivity:

If a search expression has at least one capital letter, like Qunicy, the search will then be case sensitive with respect to that term. In other words, only documents containing the word Quincy (upper case "Q") will be found.
When in doubt, use lowercase. A search term like qunicy will generate hits from documents containing the word quincy, Quincy or QUINCY.