When thinking about keywords, you may come across some which could have variations on the ending of that word, or certain words that are spelt differently.
anxiety / anxieties
theatre / theater
tire / tireless / tiresome / tirelessly
colour / color
Wildcards can be used to replace the word endings, or letters within a word. The search performed will return all results containing the alternative words. Wildcards vary per database. Each database usually has an index of the symbols available, and where they should be used.
On Library Search, wildcards are * and ?.
? is a single character search
H?ppy - happy, hippy
* is a multiple character search
Cha*ter - chapter, charter, character etc.
Temp* - temporary, temperature, temple etc.