Second Life is a virtual world - a 3D simulation of life-like environments - developed and put online in June 2003, by Linden Lab, a company based in San Francisco, USA.
At the time of this writing there were approximately 18 million users - so called “residents” - registered (but many of them are actually multiple avatars for a single individual, and most of them are not used consistently, if at all).
The main SL simulation is intended for people over 18 year of age (there are special versions for underage users).
To participate in it, you need a special “client” (an application that you have to download to your computer), available free of charge at the SL website.
Registration is free of charge, unless you choose a “premium” account (which gives you access to certain “extras” and other “privileges”).
Your free account suffices to have an avatar - an online persona (the gender is left to your choice) - and customize it to your taste (within certain limits). For the great majority of visitors the free account is more than adequate, in my opinion.
What to do there?
After you have
become familiar with the features at your disposal (for example, you can “fly” instead of walk through the virtual world), the best thing to do would be to just explore it at length. While there is a local currency - the “linden” (which you buy for real money, with your credit card) - that you can use to buy “land”, “real estate” and all sorts of virtual commodities, you don’t really need it to explore SL and even have fun during your visit.
How worthwhile it is?
I depends on what you are seeking to get out of it.
If it’s just something you’d like to see, explore, visually experience for yourself, out of sheer curiosity, then, by all means, give it a go. I don’t think you’ll regret the experience.
Some of the visual elements are breathtakingly beautiful, even though they tend to be quite similar (that’s because people are using more or less the same “ready-made” elements to build the scenery). I certainly find the “parks” and other “natural” environments the main reason for my (rare) visits there. There is also an increasing number of virtual replicas of
famous monuments (e.g. St Paul’s cathedral, in London) and other sights, so you can be a true virtual tourist. (You might want to have a look at this “guide” first: http://secondlife.com/whatis/destinationguide/.)
Sometimes, especially in time of high stress, a visit to SL felt almost like a mini vacation.
However, if you’re looking for friendship and/or romance, I would advise anyone to start looking elsewhere - like, in your FIRST life.
Mind you, I have read about people who supposedly found true friendships - and even love - in SL. (There have been quite a few “weddings” in SL. How those “marriages” are doing, that’s another question, to which I have no answer.)
On the other hand, I have also read about notorious cases of cyber-stalking, ludicrous charges of “sexual harrassment” - even “rape”! - within SL and other such idiocies, some of which ended up in court (a real-life court).
So, there IS a danger of meeting psychologically imbalanced individuals out there, who take their cartoon personas - and cartoon “life” - way too seriously. (Just think about it: who on earth would buy - with real money, because your “lindens” are ...