Question: What is a portfolio, and what should it consist of? Please include details such as the format, use of, number of items, types of items, etc.

Answer: 
A portfolio is a collection of your work. It's used to demonstrate your capabilities, usually as part of a job-seeking process. It should have your best work from whatever it is you do.

The rest is left as an exercise for the student.
A portfolio is a place where one includes their best work to show it off. Portfolio pages help in the selection criteria for business services. [Here](http://www.slideshare.net/webdesigntips/what-is-portfolio-website-design) is a slide that covers almost all about what a portfolio is and what it requires, including the importance, etc.