In many countries an academic portfolio is the required document for applications of academic staff for promotion and tenure, and also for annual professional development reviews. It summarizes your major activities and accomplishments in research, teaching and university administration − and therefore shows the overall academic experience that you bring to an institution, university or employer. Besides its usefulness in the application process (and especially so for going abroad) the portfolio is also particularly beneficial for strategic career planning and general career orientation.
However, an academic portfolio is more than just "lists". Instead of providing a compilation of publications, research contracts, projects or presentations the focus is on creating a narrative. Whereas a list reduces a person to a collection of impersonal data and does not tell anything about your personality, ambitions and way of thinking, the portfolio narrative allows you to be perceived as an individual personality standing out from the crowd.