Adjacency is a data analysis technique that can be used to extract context associated with a piece of information and improve data classification accuracy. Adjacency takes a piece of data and examines surrounding data elements, looking for designated keywords or other supporting evidence to aid in classification. For examples, the presence of the keyword "ssn" or "ss#" adjacent to a nine-digit number is a good indicator that the number represents a U.S. Social Security Number, and a date that is near a known credit card number is likely to be an expiration date, not a birthday or anniversary.