Regardless of what type of data you're working with or what kind of application you're creating, you will undoubtedly need to work with strings. No matter how the data is stored, the end user always deals in human-readable text. As such, knowing how to work with strings is part of the essential knowledge that any .NET developer needs to make rich and compelling applications.
In addition to showing you how to work with strings in the .NET Framework, this chapter will also introduce you to regular expressions. Regular expressions are format codes that not only allow you to verify that a particular string matches a given format, but you can also use regular expressions to extract meaningful information from what otherwise might be considered free-form text, such as extracting the first name from user input, or the area code from a phone number input, or the server name from a URL.