Extraordinary growth – Google+, the embryonic social network launched by Google last month, is approaching 18 million members, Mashable reports.

Quoting data from Google+ user Paul Allen who has been tracking user growth throughout July, Mashable says Google+ continues to set records as the fastest-growing social network in history although the meteoric rise in growth has begun to taper off as Paul Allen’s chart above suggests.

No matter, 18 million members in less than a month isn’t to be sneezed at.

If you’re experimenting with Google+, you’ll know it’s made available by Google as a ‘field trial,’ Google’s way of saying it’s a beta, some things don’t yet work properly, other things will change and new features will arrive. There are a number of very good introductory guides to Google+, such as:

• Google+ Demo from Google
• How To Use Google Plus by ReadWriteWeb
• Google+: The Complete Guide by Mashable

I’ve been experimenting with Google+ for some weeks and Shel and I talked about it in FIR 606 earlier this month. Shel’s written a useful guide to Google+ from a business-use perspective. We also experimented with Google+Hangouts, the informal video-conferencing feature, that gave us mixed results in this early stage of its development (and see what some companies are thinking about with Google+Hangouts – Dell and customer service, for instance.

To join Google+, you’ll need an invitation until such time as Google make it wholly open. If you’d like one and would like to join me on Google+, just ask: all I need is your name and your email address plus a simple reason why you want to sign up.