A name is a string of characters used to identify some entity in a program. C# imposes no limit on the length of names and all characters are significant (meaning that they are case sensitive).

However, identifiers in C# must obey the following rules (Jones, 2001)

1. starts with either
   1. letters, or
   2. underscore character
2. contains only
   1. letters
   2. digits
   3. underscore character
3. must not be a keyword or a reserved word (which can be “escaped” by prefixing with the verbatim character @)

References

1. Jones, B. L. (2001, December 14). Storing Information with Variables in C#. Retrieved from http://www.informit.com/articles/article.aspx?p=24472