Prims are meshes, mostly 3D, although Sculpted Prims can be 2-dimensional.
Objects are formal groups of prims, linked to each other, with one prim in the object set defined as "root"
Objects used to have the ability to group themselves in a slightly less formal way via Joints
Textures are raster images.
Sculpted prims require a specially formulated texture in order to be "sculpted".
SL Inventory seems to make a distinction between textures and Photos (images saved to file of what the viewer was rendering at a given moment in time).
Animations are supported by composting each frame of an animation sequence into a single tile.
Terrain can be uploaded as a 13 channel RAW file, although currently only the RGB channels are used to affect terrain.
- Red : Height field
- Green : Height field multiplier
- Blue : Water table (Second Life currently only supports a single, sim-wide water table, although adjacent regions can have their water table at different altitudes)
Plain text documents that can have other assets embedded within them.
LSL code in a plain text file for editing. Scripts can only "run" while existing in a prim's inventory, though they can be stored in a non-running state in both prim and Resident inventories.
Gestures can have sounds and animations applied to them.
Body parts can have textures applied to them.
Linden Dollars are used to enable commerce in Second Life.