Some databases assume that words typed next to each other should be searched as phrases.
Others automatically put a Boolean AND between your search terms, requiring that all the words be present, but not necessarily adjacent to each other.
These searches can retrieve very different results.
Using parentheses or quotes around search words is a common way to do phrase searching, but not all databases or search engines use them.
Example: "genetic engineering" or (genetic engineering)
PROXIMITY SEARCH BASICS
Many databases allow you to specify that the words you are searching are within a certain proximity of each other.
Because of their proximity the two words can have a relationship
Proximity operators are more specific than Boolean operators and make your search more precise.
Proximity operators also vary by database, but some common ones include:W# (With, Within) and N# (Near)
W# can specify that words appear in the order you type them
Substitute the # with a number of words that may appear in between. If no number is given, then it specifies an exact phrase.
Examples: coldW2therapy, it retrieves: cold therapy, cold water therapy, etc.)
N# can specify that the words may appear in any order.
Substitute the # with a number of words that may appear in between.
Examples: cloningN3human, it retrieves: cloning of humans, human cloning etc.)
Proximity Operators vary from database to database (ADJ#, W/#, N/#, NEAR#, etc), you need to check the Help section of each database to see what they use, look for Proximity Operators or Proximity Searching