Truncation allows you to find multiple spelling variations of a keyword in your search.
A universal symbol for truncation is the asterisk (*).
Used at the end of a root, it can return variations on spelling from the point of the asterisk. Consult the "Help" section for the database you are using to find out exactly which truncation symbol is used in that database.
Using a wildcard in a search term allows you to substitute a symbol for a letter in a word. This symbol represents variations in spelling. Wildcards may vary by database and not every database allows for wildcard searching (for example, PubMed does not).
To determine which symbol will best suit your needs, check out the Help section of the database you are using. See the Help notes on Truncation or Wildcards.