I'll say it from the outset, I'm a big fan of LinkedIn. If you are not using it, why not? You really should be. It takes very little effort once you have set it up and can be an incredibly useful tool in reconnecting with previous colleagues and staying in touch with your professional network.

Recently, LinkedIn passed over 100 million members worldwide, with over 1 million members based in Australia. Some quick stats:

• 58.9% Male vs 41.1% Female
• Over 70% between ages 25 – 54
• If LinkedIn were a country – it would be 12 largest worldwide
• LinkedIn is adding a million users every 12 days

Check out these sources for more information and where I got the above stats from:

• http://www.slideshare.net/amover/linked-in-demographics-and-statistics-2011
• http://blog.linkedin.com/100million/
• http://mashable.com/2011/03/24/linkedin-overview-infographic/

Given the numbers, I don't understand why any professional, or business owner for that matter, would not establish a LinkedIn profile.

One of the primary reasons I have come across with why people are not on LinkedIn is to do with it's perception next to Facebook. For those people who are not on Facebook, they paint LinkedIn with the same brush, so to speak. Basically protective of their privacy and not wanting to update on everything in their lives. For those that are already on Facebook, they think why should they engage with another channel online.

Here's my top 5 reasons for getting on LinkedIn:

1. LinkedIn is purely professional. Unlike Facebook, you are not sharing photo's or getting tagged with photo's, there are no games cluttering the experience (Farmviille, Mafia Wars, etc) and you don't have to enter your private information such as birthday & marital status. It is your online resume or CV.

2. Ex-colleague reconnection. Think about your career. If you have worked internationally, interstate or even just changed organisation at some point in your career, then you have most likely lost contact with a big portion of your colleagues. LinkedIn is a great way of getting reconnected (of course, it should only be with the ones you liked/got along with.

3. Friends connection. Think about your family, friends and close acquaintances. Do you know what they actually do? By connecting on LinkedIn, it's an easy way to better understand what they do and for opportunities to be uncovered that can benefit both of you.

4. Recommendation can become visible. LinkedIn has functionality that allows you to request recommendations. Once the recommendation is sent, you will be notified to approve it before it becomes public.

5. Allows you to share your knowledge. Using your update you can share interesting articles, thoughts and information which can benefit your network. It reminds your network of what you know and how you may be able to help them.

So what are you waiting for? Get active on LinkedIn. Oh..and here's my LinkedIn profile page