Dichotomous key

(a) A means of assigning an organism to a specific taxonomic category typically involves the use of specific criteria that may be posed as questions (e.g., what does the organism look like? etc.)
(b Relevant criteria may be arranged as a dichotomous key
(c)In a dichotomous key questions are arranged hierarchically (just as taxonomic categories are) with more general questions (i.e., those arranging organisms into large categories) are asked first, with questions becoming more specific (better suited to arranging organisms into more specific taxa) asked subsequently
(d) In addition, questions are dichotomous, meaning that they each have two possible answers, with each answer distinguishing the organisms as well as the path to the next question