Search looks for exact, case-insensitive keywords; keywords shorter than a minimum length are ignored.
Use upper-case OR to get more results. Example: cat OR dog (content contains either "cat" or "dog").
You can use upper-case AND to require all words, but this is the same as the default behavior. Example: cat AND dog (same as cat dog, content must contain both "cat" and "dog").
Use quotes to search for a phrase. Example: "the cat eats mice".
You can precede keywords by - to exclude them; you must still have at least one "positive" keyword. Example: cat -dog (content must contain cat and cannot contain dog).