For research use only. Not for use in diagnostic procedures.
A regular expression (regex), also called a rational expression, is a sequence of alphanumeric and/or special characters that can define a search pattern depending on their context. The basic premise is that such patterns can result in filtering of data and other functionalities (such as find and replace) within software and other computer applications.
A good resource to learn about (and practice using) regular expressions is at the RegexOne website: https://regexone.com/