ALTE is the Association of Language Testers in Europe.
It has developed a set of descriptors for language exams which say what a language learner at a particular level is able to achieve (i.e. understand or produce, etc).
ALTE was founded by the Universities of Cambridge and Salamanca for the Cambridge exams; however other exam boards have related their exams to the same system. It now includes over 30 examination and educational bodies from around Europe and does not restrict itself to English alone, also including a number of other European languages.
ALTE have also sponsored a number of conferences to promote their system.
Learner Levels for English Language Students – more on learner levels
Official Website – official website for ALTE[ratings]