Avatars in Second Life
From Sl Wiki
Avatar is the term for a virtual body used to represent you, the Second Life user. Although an ancient word, it derives its SL meaning from Neal Stephenson's cyberpunk sci-fi classic, Snow Crash(1992) - a book that inspired many developers to build virtual worlds, and that also gave us the term "Metaverse", often taken to refer to the (still distant!) 3D internet.
On registering for Second Life you will need to select a name for your in-world persona, your avatar. Unless you are a company prepared to pay unnecessarily large sums of money for a tailored surname, you will be presented with a list of currently available surnames from which you must select one. You are free to choose your own forename.
As a new resident, on entering Second Life you will be taken through a set of tutorials to teach you the basics, such as how to move (and fly!), select items, chat and so on. Part of the entry process is the selection and basic modification of your avatar. Second Life supplies a number of basic avatars (male, female and... errm... rabbit!) for you to choose from. You are then shown how to modify this basic avatar. Within certain limits, you can change most of your avatar's features: hair, skin, eyes, headshape, torso shape, arms, legs... the list is lengthy. You can also change clothing to some extent.
You are free to edit your appearance any time in-world.
Alts
It is common for people to have several alternative avatar bodies - or "alts". And they may not all be the same gender, or indeed, species... In fact alts can be pretty much anything: anime characters; dragons (oddly popular choice); inanimate objects - anything at all really. "40ft Felix The Cat, anyone?"
If you really like your SL Avatar, you can get it made into a Real Life model by fabjectory