26 August 2010
A symbol is a graphic, button, or movie clip that you create manually in Adobe Flash Professional or by using the Button (ActionScript 2), SimpleButton (ActionScript 3), and MovieClip classes. Once you've converted an object to a symbol, the symbol appears in the Library and you can reuse the symbol by dragging out instances of it throughout your document. You can also copy symbols to use in other documents.
A symbol can include artwork that you import from another application. Any symbol that you create automatically becomes part of the Library for the current document.
An instance is a copy of a symbol located on the Stage or nested inside another symbol. An instance can be different from its parent symbol in color, size, transparency, and function. When you edit the symbol directly, Flash updates all of its instances. Conversely, you can apply effects and transformations to an instance of a symbol and only update that specific instance.
Using symbols in your documents dramatically reduces file size; saving several instances of a symbol requires much less storage space than saving multiple copies of the contents of the symbol. For example, you can reduce the file size of your documents by converting static graphics, such as background images, into symbols and then reusing them. Using symbols can also speeds SWF file playback because each symbol needs to be downloaded to Flash Player only once.
To convert a selected element or elements to a symbol, follow these steps:
Flash adds the symbol to the Library. The corresponding icon indicates whether the symbol is a button, graphic, or movie clip.
To learn more about working with symbols, watch the video titled Symbols, instances, and the Library panel.