The three generally accepted primary domains of learning are cognitive, psycho-motor and affective. While not all agrees on which domain is the most important, most do at least agree that measuring the affective domain is the most challenging.
Each domain has its own taxonomy of learning, and typically, there are more than one taxonomy. The most well-known and widely used cognitive taxonomy is Bloom’s taxonomy. Both Simpson’s and Allan’s taxonomies on the psycho-motor domain are popular while for the affective domain, Krathwohl’s is common.
There is a reasonable good and concise document that describes the levels of each of these three taxonomies, based on Bloom’s Cognitive, Simpson’s Psycho-motor and Krathwohl’s Affective taxonomies respectively. Click here to access the document.