Filters and limits do exactly what they sound like they do--they remove unwanted results based on certain criteria that you select. In many databases, filters and/or limits include:
Using filters can be useful for many reasons--you may need to restrict your results to articles published within the last five or ten years, you may have retrieved a large number of articles that were written in another language, you may need to look at just the articles published within your field, etc. Limits and filters are located in different places within databases. If you need help locating and using filters or limits in a particular database, ask your liaison librarian or see the help sheets for the specific database.
Wildcards represent variations within a word, either because you want multiple spellings of a word to be caught or because you are not certain of how something is spelled. Wildcards take different forms but are usually either an asterisk (*) or a question mark (?). The wildcard tells the search engine or database that you are willing to accept substitute letters in the spot where the wildcard is located.
e.g. hospital* would give you:
hospital, hospitals, hospitalized, hospitalization, hospitalize, and many other forms of the word
*Use prudently, because you may get far more results than you need when using a wildcard. The above example would also return terms such as: hospitality, hospitalocynism, and all foreign spellings.
Double Quotation Marks
Within databases, placing a phrase in quotation marks generally guarantees that the search results you get will have the words in the exact order and spelling in which you typed them. For instance, if you wanted articles that discussed psychosocial support, the database would possibly split those two terms apart, searching for an article that used the term psychosocial and the term support, but not necessarily together, as a unified concept. Typing "psychosocial support" in double quotation marks would fix that problem.
Note that using a phrase in quotation marks probably means that you will miss any articles with different spelling and that the database will not return any suggested subject terms. Phrases in double quotation marks should be restricted to concepts that are not listed in the subject headings of the database, such as "head cooling".