Keeping a portfolio also helps you reflect about that 'professional brand' ... in other words it can be a tool for self-reflection. In that sense it is not used to simply 'show off'.Â
Thinking about and looking back at what you have done and are doing helps define your interests and come up with new goals that are aligned with your learning path/life.
If the portfolio exposes all of this (in the sense of 'professional branding') to an audience (a mentor, teacher, peer, possible future employee, ...) that would then interact with you as a student on this, the self-reflective process would become more interesting as your identity, seen from sociological point of view, is 'constructed' through social interaction
Digital portfolios allow for practicing digital citizenship, get Googled, share quality projects for college entrance, provide authentic connections outside the classroom, show understanding etc.
Portfolios help students develop a sense of belonging and to own their learning. I think their power goes beyond helping students document their work and learning experience. Their historical value has an immense impact on curriculum design and evaluation, as well as in the documentation of Approaches to Teaching and Learning. We are living in times where the sense of authorship is a must, when the information 'that needs to go in books' will be outdated by the time it is published, so portfolios give us an edge on that.
The most important value of a digital portfolio is the intrinsic boost to a student's self-confidence. They can clearly see their own accomplishments. That self-confidence is a key to the student's future success.
To focus the question a bit, in the higher education context keeping a collection of written work and associated research via blog or portfolio can be an excellent way to introduce technical skills that may not be addressed in other courses, e.g. basic coding by introduction to markdown, etc. (Bharati)
Other Important Advantages:
Accessibility:
Portfolios in digital format can be easily and inexpensively reproduced therefore materials can be made available to a wider audience
Can be accessible from multiple locations and by many individuals simultaneously e.g., on the WWW
Portability: Easier to transport than hard copy versions.
Creativity: New non-linear formats and the integration of various media types allow students many ways to creatively express their professional knowledge and skills.
Technology:
Digital portfolios are one of the best ways for students to communicate their knowledge and expertise related to their use of technology
Students can demonstrate proof of their technical skills while also displaying their ability to apply technology in the creation of multimedia presentations, software programs and the like
Self-confidence: Building technology skills and fostering self-confidence in their own abilities.
Community: Sharing ideas and resources. (Wikispaces)
A key benefit of digital portfolios is their versatility. It is easy to update them and keep them current. Users can organize and tailor information toward a specific use, be it to demonstrate mastery of a certain subject or to apply for an internship or a job. Digital portfolios can be a visually interesting medium for presenting disparate information. (Mackosfsky)
References:
Bharati, Prasanna. Retrieved from http://edtechreview.in/trends-insights/insights/1537-how-do-digital-portfolios-help-students
Mackosfsky, Nina. Retrieved from http://classroom.synonym.com/digital-portfolio-2449.html
Wikispaces. https://digitalportfolio.wikispaces.com/What+is+a+digital+portfolio%3F