Measures are a custom condition based on data to define logic which can be used in segmentation. Measures would typically be a DateTime or Numeric type. Measures are also often aggregates i.e., maximum, minimum, count, sum, average, first, last.
If you select 'measure' from a drop down box when segmenting data you will see the below standard measures list.
Examples of standard measures:
Total distinct opens last X days...
Last open date
Total distinct emails clicked in last X days...
Last clicked date
Total distinct forms submitted last X days
Last form submitted form date
You can then create customised measures if required, by consulting with a TractionNext developer.