All the icons - help me figure them out!

What do all the different icons mean in my inventory? Off the top of my head I don't know what the little dancing guy is. Is there a comprehensive guide to the icons anywhere?

The little dancing guy is an animation. By using this animation, your avatar will start moving around/dancing/sitting/etc

The brown square with a figure in it is your "shape" which defines the size of your nose, length of your arms, etc

The plain white figure is your "skin" which is makeup and shading to put over your shape

A Box is an object. This can be "rezzed" or placed in the world, or "worn" as an attachment. Sometimes you might see a bunch of boxes stacked together in your inventory, like a bunch of blocks. This means the object is a bunch of objects that are linked together to form one big object.

Then there are shirts, undershirts, skirts, pants, jackets, and shoes. Also, eyeballs, which you might want to "wear" unless you want to walk around with zombie eyes.

Thanks for all the info!

How do I activate an animation?

Open your inventory and pick File / Show Filters for a little cheat sheet. Just don't change the checkboxes .

Calling Cards - you get one whenever someone offers friendship or their calling card specifically, they're mostly useless

Gestures - a grouped set of actions you can play in response to a trigger (ie /gasp could play an animation of holding your hand in front of your mouth and saying "Kitty Barnett gasps" - usually just annoying)

Landmarks - SL's equivalent of a "bookmark/favourites". You can create one in World / "Create Landmark Here"

Objects - anything made up of prims. In some cases you'll rez it in-world (ie furniture), in other cases you'll attach it (ie hair)

Textures and Snapshots are really the same thing. The difference is if you take a snapshot in-world and upload it you get the snapshot icon, if you upload an image you get the texture icon

Icons that don't show there are skin (little avie with hands and legs outward), shape (looks like a little framed picture).

Clothing is grouped together but consists of several predetermined layers with similar looking items.
For the top part of your avie you have: Undershirt, Shirt, Jacket and Gloves
For the bottom part of your avie you have; Underpants, Socks, Pants, Skirt and Shoes

Don't try to think of the clothing icons as representative (you can have a jacket on a (under)shirt layer), but just the order things will get shown in: Jacket covers Shirt covers Undershirt.

Oh golly, I'm not inworld right now, but if memory serves, just double click on it? Or maybe right-click on it in your inventory and select 'wear'? You should get another little window that pops up that represents the animation (chicken dance, e.g.) that will let you 'stop', 'play in world' (so everyone can see you) or 'play locally' (just on your PC or client machine).

If you get totally stuck doing an animation, there's an option in the Tool menu to "stop all animations."

Double click and choose either to play in world or locally (only you can see it).

Oh, and gestures kind of look like a yelling guy.

Right-click on it and pick "Play in World". To stop: click the Stop button on the dialog that pops up (or just close it)

(Alternatively, you could have double-clicked on it in inventory and clicked the "Play in World" button)

(Play locally means only you see the animation and noone else does)

In general, I wouldn't obsess too much about knowing what every last little thing means or does, but just pick things up as you go along and eventually you'll either know what it does because someone explained it, or you just went ahead and found out for yourself .