Most search tools default to searching for your keywords in the title, author, subject heading and abstract of a document.
Searching within the full text differs from this in that when you set up a search to search within the full text, not only are you searching within the title, author, subject headings, and abstract fields, you are searching within the full text of the document itself.
Searching within the full text is particularly useful if you're trying to focus in on a very specific word or phrase which you are having difficulty finding.
It is also very useful when searching ebook collections, as you can skip to the instances of the words or phrases you searched, without having to browse through entire books, which can be a timesaver.
Most databases will have a search option to search within the full text, which you can toggle on and off as required.
Refer to the help guide of the search tool you are using to determine if this is an option.
Searching within the full text often yields many more results, some of which will be irrelevant, so more thorough vetting of the results set is required. It's a bit of a tradeoff -- what you lose in precision you gain in a more thorough search of the documents. If you find you are getting too many irrelevant results when searching within the full text, revert back to the default search settings.
Proximity searching is a form of advanced search which allows users to look for strings of words within a given distance of each other in a document. Users can specify how close keywords should appear to one another.
e.g. A search could be used to find "Internet education", and match phrases such as "education over the Internet" or "use of Internet in various education settings" -- all of which would be relevant.
Proximity searching helps to avoid search results where the words are scattered across a page or a document, unrelated to one another, and helps to return more relevant results.
NEAR operator - finds words within a specified distance of one another, in any order.
e.g. tax N5 reform
The words tax and reform must appear in a document within 5 words of one another, regardless of order.
WITHIN operator - finds words within a specified distance of one another, in the same order in which you entered them.
ADJ operator - ADJ stands for adjacent, and works the same way as "phrase searching" in that it finds keywords that are adjacent to one another in the text.
e.g. welfare ADJ reform is the same as "welfare reform"
Variations: NEAR or N(and a number), ADJ, WITH or W(and a number)
Refer to the help guide of the search tool you are using to determine if proximity searching is an option.