Social networks more popular than ever. According to research by consultants Burson-Marsteller into the Fortune 100 top companies, 87% of big companies use at least one social network, up from 84% in 2011; but 70% of companies update their presence every day on Facebook, Twitter or YouTube. Facebook is mostly used for marketing and Twitter for public relations, to influence public opinion. Twitter is the most popular among companies, used by 82% of the Top 100 companies in 2012, compared with...