Linkedln is a social networking site for professionals. It (A1) ... in 2003 and it (A2) ... mainly for professional networking. The number of Linkedln users is increasing very fast: two new members join the website every second. It now has over 875 million users, and 40% of them check their profile every day. Professionals nowadays use the site to find jobs and business opportunities, and companies search for potential candidates. Users can follow different companies and also see who (A3) ... their profile page. Other features include groups and online conversations. It is estimated that over 200 conversations (A4) ... place right now.