Right after I started this column I received several friend requests on Facebook. While I was flattered by the compliments, I was in a dilemma about whether to accept or ignore their requests. Did I really want strangers to have access to my everyday babblings, photos, or other personal details?

In real life, it's easy to separate your professional identity from your personal one. Suits for co-workers, jeans for friends. Wine at office parties, beer for hanging out. High heels at work, sandals at your buddy's place. But what to do when all friends and professional contacts can gather in the same place, at any given time of the day? Social networking sites have made it easy for people to connect with each other with a click, but have also made it difficult to maintain a distance between one's personal and professional online identities.

For a long time, I was hesitant to expand the network of my friends on Facebook beyond 'real' friends. Friend request from an acquaintance at the office? Ignore. Someone I met at a business meeting just once? Ignore. I chose to keep my online connections limited to my personal contacts.

But the extended interactions that such online networking sites allow are becoming increasingly important in professional and business development. Facebook has over 600 million users, Twitter over 100 million and LinkedIn over 70 million. Having networks with even a fraction of these users can mean a lot if you want to promote your company, your product, an event you are organising, or even just yourself.

Today, advertising on a social networking site has become an essential part of a product marketing strategy. Such sites offer real-time social networks, which means that you can reach your audience quickly and promote your product. The fantastic part of networking is that your reach is unlimited, yet you can add a personal touch. What you put out in your primary circle has a snowballing effect, and can be shared or retweeted to a million others. The impact is much more than with traditional promotion media.

These networks also come in handy if you are looking for a job or offering one. In fact, networking sites are now listed alongside job search sites. Relationships that you make with business acquaintances online can have a profitable impact on future dealings. Making your online presence felt can be an advantage for your professional development. And all this…for free!

So does this mean you add everyone and accept every other friend request? You might want to be able to complain about your work on Facebook or MySpace without your 'friended' boss raising an eyebrow, or swear about a meeting gone badly without the client, who may follow you on Twitter, reading it.

The answer is discretion – in terms of who you add to your networks, how you express yourself on your networks, and barring this, using privacy settings that limit what your contacts are able to access. Certain sites understand the difference between their personal and commercial utility and enable users to create secondary pages, specifically for business purposes. There are also sites that are more suited for connecting business professionals, such as LinkedIn.

Social networking sites are now a vital part of our online experience. For most, it is the second site they login to after checking their email. Such sites present an opportunity to reach out to an unlimited number of people. If this reach can be used for business advantages, then why not?