Hey Jane! Yes, by portfolio I mean a website with a collection of your work. Here is a great podcast talking about customizing portfolios that you might enjoy https://shoptalkshow.com/329-dan-mall-building-portfolio/
Thanks for your comment. I do think it varies by industry. I also think the biggest predictor (in my experience at least) is # years of continuous work experience (including presently working) in the same job title. Otherwise I find it's a super low response rate. Have a great one!