to classify

verb
  1. To arrange or organize by classes; to categorize or sort into groups based on shared characteristics or criteria. verb
    Scientists often need to classify organisms into different species based on their characteristics.
    The library uses a system to classify books by subject matter.
  2. To designate or regard as belonging to a particular category, often for purposes of analysis or study. verb
    The government decided to classify the document as top secret.
    In the study, participants were classified according to age and gender.