These general search tips apply to most search engines, subject databases, library catalogues, and other discovery services.
Upper and lower case letters, special characters, umlauts
If the spelling of a term is not clear to you or if you want to find a term in different spellings / forms / languages at the same time, use wildcards. The asterisk (*) often replaces any number of characters, the question mark (?) exactly one character.
In some search services, wildcards cannot be used at all, or can only be used at the end of a word, or only the asterisk can be used and not the question mark. As a rule, you cannot use wildcards at the beginning of a word.
Word forms / automatic wildcards
Some search services perform an automatic search for further word forms or similar terms or always add a wildcard at the end of a search term without you having to enter it. In these cases it can happen that you switch off the automatic search for word forms or similar by putting an asterisk and therefore you get less hits than without a wildcard. In some search services, you may also have to select quotation marks or special search fields in order to perform an "exact search" (without wildcards).
There are several ways to combine several search terms within one search field or terms in different search fields. Many databases offer the following options:
Find all terms (AND)
Use the word AND (in capitals), the plus sign or simply the space bar to get hits that contain all search terms.
If you use space bar, usually the hits will be displayed first where all search terms occur and then those that contain only some or one of the entered search terms.
Word groups (phrase search)
Use quotation marks to get only hits where the search terms appear directly next to each other (in a specific order).
Find one or more terms (OR)
Use the word OR (in capitals) or the brackets (...) to get hits with either one or the other (or both) search terms.
Since the search range is greatly expanded with an OR operation, you will often find a large number of hits. Therefore it is useful to add another term to the search, which must occur (AND or phrase).
Note here whether and how a search engine combines the terms, because the search for film AND star OR stern could also be interpreted by a search engine as searching for the terms film and star or for the single term star.
Exclude terms (NOT)
Use the word NOT (in capitals) or the minus sign to get only hits that include the first search term but not the second.
Note that some search engines do not consider the word NOT as "exclude terms" and instead search for the German word "Not".
Please also note that you can use NOT to exclude pages that actually match your search query. A page with the title "This is about Star Wars not Star Trek" would still not be found with the search for star -trek because the word trek appears on the page.