Collaborative Application Markup Language (CAML) is an XML-based language used in SharePoint for querying lists, defining views, defining list fields, and other tasks.
Source and more on github
Building a Dev API
Validating CamlQuery syntax (not ready yet)
SharePoint in general does not give helpful error messages when presented with incorrect Syntax in a CAML query, whether it's malformed XML, a misspelled element name, or any other sort of error. While this is a secondary use case, and not the reason I wrote this library, I do hope that as this library becomes more feature complete that this will become a potential use for it, especially for the case of generated CAML queries.