A majority (79%) of information technology (IT) professionals use social networking sites such as Facebook and YouTube, but 21 percent do not use social networking sites at all, according to a new survey by CompTIA.

Of the major social networking sites, Facebook was the most popular, with 57 percent of respondents reporting they had been active on the site within the past 30 days. YouTube was the second most popular site (53%), then MySpace (29%), Twitter (25%) and LinkedIn (22%).