Here’s a breakdown of the key levels:
Level 0 – Unable to speak the language in almost any context.
Level 1 – Able to maintain simple exchanges on topics related to self, despite pervasive errors and limited contextual appropriateness.
Level 2 – Able to communicate intended meaning in straightforward, everyday conversations and routine, work-related interactions.
Level 3 – Able to speak with sufficient accuracy to participate effectively in formal and informal contexts on general social and professional topics and tasks.
Level 4 – Able to speak with considerable precision using culturally appropriate and language tailored to a variety of audiences on a wide range of topics.
Level 5 – Able to speak with clarity of expression and precision, using diverse linguistic resources to produce articulate, nuanced, and engaging language in almost any context.
Each level includes further sublevels (i.e, 0+,1+, 2+, 3+, and 4+) to specify proficiency nuances within a given level.