Searching for Phrases
To run a keyword search for an exact phrase, enclose the phrase in double quotes.
Only the exact terms within the quotes are searched, no matter which search mode is selected.

The query
"merger agreement" will not hit on a document
that only contains the sentence:
Mutual merger agreements have been signed.
The reason is the document does not contain the exact term agreement.
When searching for phrases, stop words are also searched.

The query "merger and agreement" will match only documents containing the exact phrase merger and agreement even though and is a stop word.
The query "and" with no other terms in the quotes will not return any documents. A single term enclosed in quotes is interpreted as a plain exact match search, and plain exact match searches ignore stop words.