Portfolios come in a variety of formats: paper, VHS, HTML, Flash, database-driven, or combinations of formats. Most people are moving toward digital portfolios because of ease of access and editing. In some circumstances, paper portfolios still make sense - for example, art and teaching students may have tangible artifacts that lose value when scanned or otherwise digitized. Portfolios that are primarily concerned with reflection and not presentation may also work well as plain text documents, which essentially eliminates any technological learning curve.
Portfolios can be created and used by a number of different entities.
Student portfolios are most common, and are used for getting a job, passing a class, or reflecting on their development.
Faculty portfolios are used for tenure review and to assess one's teaching. Faculty may also look at the portfolios their students make to assess the students, or to draw samples for the portfolios they themselves create.
Institutional portfolios are usually used for accreditation reviews. Institutions may also look at data in faculty and student portfolios to get a picture of how well students are learning, how well faculty are teaching, and how well the institution is succeeding in its mission.