In just a few short years, social networking Web sites and applications have gone from a novelty used mostly by youth to a critical component in defining one's professional profile. At a Science Alliance webinar on September 9, 2009, Lisa B. Marshall and Marc A. Wolfe explained how to build an online presence geared toward career advancement. The two communications specialists detailed specific steps to take including reviewing your current presence, removing anything that could damage your professional reputation, and building a profile on a number of general and niche networking sites, such as LinkedIn and Nature Network. They also discussed how to makeover your profile and keep it fresh.