Wildcards are used to represent unknown or variant characters within a word. (The truncation symbol from the basic search tools box is also a wildcard)
Not every search tool is universal and can be used across multiple databases although, generally, if two databases are produced by the same company they are likely to use the same symbols.
In the EBSCO databases1 there are two symbols that can be used to look for variant characters.
If you're looking for a difference between e.g. the UK or US spelling of a word where the UK spelling has an extra letter then the symbol you use in an EBSCO database to symbolise this is the hashtag # and you place this within the word where the extra letter could be. So it would look like this: behavio#r and this tells the database to look for both behavior and behaviour and put them into your results.
If the difference is not through the addition / subtraction of a character but substitution e.g. organize with a 'z' versus organise with an 's' then the symbol you'd use would be a question mark ? and, again, you'd place this within the word where the substitute letter is located. So it would look like this: organi?e
You can also use the ? for an 'unknown' character e.g. ne?t would find neat / next / nest etc. but if you use it in this way the word must be at least four characters long. Any shorter and the ? will not work.
You can use these symbols with phrase searching at the same time.
1 Library Plus / Medline / CINAHL Complete / AMED / SportDISCUS / Business Source Complete / PsycINFO / Hospitality & Tourism Index / Science Full Text Select / Criminal Justice Abstracts etc.
In the Web of Science database there are some differences in search symbols and how they work.
The question mark ? is used in the same way to look for substitution characters, so wom?n will find woman / women
You can use a dollar symbol $ to search for the presence / absence of a character (in the same way you'd use # in an EBSCO database) e.g. colo$r would find color / colour; but you could also use it at the end of a word e.g. grain$ to find grain / grains. Because the $ only represents zero or one character it won't find grainy / grained etc. You would have to use right-hand truncation for that.
The asterisk works slightly differently in the Web of Science as you can use it to either the left or the right of a word, so it doesn't have to be at the end. But there are rules!
For left-handed truncation there must be at least three characters after the wildcard in order for the search to work. So *bio would work but *bi would not (*bio would find you bio / biography / biographical / autobiography / autobiographer etc.)
For right-handed truncation there must be at least three characters before the wildcard in order for the search to work. So sea* would work but zy* would not (sea* would get you sea / seaweed / seaside / seashore / season / seasonal / seated etc. depending on where you searched)
There are more search options, wildcards and tools for the Web of Science that you can use. Go into the database, and when you're on the search screen for the type of search you want to do (basic / advanced) click on the Help tab in the top-right of the screen. The help is tailored to the page you're on so if you want advanced options then make sure you're on the advanced search screen.