As the word portfolio suggests, they can be a collection of writings, annotations, achievements, and evidential documentation that together describe a student's learning experiences, their reflections on these experiences and the outcomes of this for their continuing development.
Portfolios can be a useful way of collecting evidence of learning to meet a learning contract.
They are often a collection of materials and entries of diverse nature gathered over the course and put together in some structured way to provide evidence of learning and development. McGill, I. and L. Beaty, Action Learning in Higher Education, in Action Learning. Assessment of each student is by the production of a personal portfolio, through which students demonstrate achievement of their competences. During the course, students produce a mixture of individual assignments and group projects. These, together with other materials, for example, logbooks and relevant work experience, form the portfolio.