A set of contiguous alphanumeric characters.  Strings are text, such as names, addresses and descriptions.  In programming, strings are always quoted; for example, 
state="New York".  The quote at the end of the string is actually the necessary marker.  Were it not quoted, the programming logic to determine the end of the text could be extremely complicated in certain situations.  See 
alphanumeric.
Although a string may include numeric digits, they are normally not numbers used for calculation.  If they were, they would have to be copied to a numeric structure for an arithmetic operation.  Contrast with 
numeric data.  See 
string literal, 
string handling, 
quoted search and 
account number.