The technical debt metaphor describes the effect of immature artifacts on software maintenance that bring a short-term benefit to the project in terms of increased productivity and lower cost, but that may have to be paid off with interest later. 

Software evolution generally deals with large amounts of data, as one must look at whole project histories as opposed to their current snapshot. 

Software visualization aims to help people to understand software through the use of visual resources. It can be effectively used to analyze and understand the large amount of data produced during software evolution.