Competency in 21st-century health communication involves an understanding that the internet landscape has evolved from static webpages to applications that engage users. This evolution to "Web 2.0" includes such applications as blogs, wikis, social-networking sites, and podcasts. This review presents trends in Web 2.0 internet usage, summarizes Web 2.0 applications as platforms for health promotion, discusses guidelines for using Web 2.0 applications, and identifies Web 2.0 learning outcomes. Greater awareness of Web 2.0 can provide health educators with new channels for health communication and will help stimulate additional research to further define best-practice models. (Contains 3 tables.)