Each time a learner acquires new knowledge, she must in some way put in relation what she already knew and what she just discovered. The goal is the achievement of a new awareness that allows the learner to see from a higher viewpoint her personal know-how, and the imbalances and gaps yet to be fulfilled by further study.
The goal of an e-portfolio is in fact the one of capturing the performance, the learning processes, the choices, the different understanding modes, the reasons and motivations, the progress made and the cultural and learning context in which the learning experience takes place.
"If your view of portfolios is just something akin to a content management system, don't bother. But if it's the student's personal and continuing presence in an online community of discourse, then you are on to something."(Stephen Downes)