BPMN is the abbreviation of Business Process Model and Notation is a visual language used to represent business processes schematically. Like almost every language, BPMN is bound by semantic principles. These are articulated in the formal specifications for BPMN drawn up by the OMG. The language has a strong relationship with the well known traditional flowchartering. Although flowchartering had a number of drawbacks, it was highly appreciated by users ("the business") due to the fact that the symbols used and the logic embedded in flowchartering were considered very "readable". BPMN has therefore adopted a lot of flowchartering symbols and left their meaning unchanged. However, there are semantic rules attached to the way these symbols should be used (the lack of semantic rules was one of the disadvantages of flowchartering).
The OMG has chosen to distinguish 3 levels within the symbol set of BPMN:
Level 1 is the level at which people exchange thoughts with the business about the business processes. It contains many symbols that were/are also applicable in the flowchartering technique.
Level 2 is the level at which the programmers/configurators exchange ideas about the business processes. It is a more technical level on which more specific process behaviour is expressed.
Level 3 is the level at which, based on the symbol set used, software is automatically generated to support business processes. This level is currently not part of the course.