[private]About symbols
A symbol is an art object that you can reuse in a document. For example, if you create a symbol from a flower, you can then add instances of that symbol multiple times to your artwork without actually adding the complex art multiple times. Each symbol instance is linked to the symbol in the Symbols palette or a symbols library. Using symbols can save you time and greatly reduce file size. Symbols also provide excellent support for SWF and SVG export.
After you place a symbol, you can edit the symbol’s instances on the artboard and, if you want, redefine the original symbol with the edits. The symbolism tools let you add and manipulate multiple symbol instances at once.

Symbol libraries and the Symbols palette
Symbol libraries are collections of preset symbols, available from the Window > Symbol Libraries submenu or the Open Symbol Library submenu in the Symbols palette menu.
When you open a symbol library, it appears in a new palette (not the Symbols palette). You select, sort, and view items in a symbol library the same as you do in the Symbols palette. However, you can’t add items to, delete items from, or edit the items in symbol libraries.[/private]