The document outlines five types of professional learning networks (PLNs) for teachers: 1) casts like podcasts and vidcasts, 2) social networks like Facebook and NING, 3) blogs, 4) microblogging like Twitter, and 5) social bookmarking sites like Pinterest and Diigo. It provides examples of how teachers use each type as a PLN, such as using podcasts for ESL education, connecting through Facebook science education groups, following blogs about educational technology, using Twitter hashtags like #Twitter4Teachers, and bookmarking lesson plans on Pinterest.