Symbols are reusable graphics that you create with the drawing tools. When you place a symbol on the Stage or inside another symbol, you create an instance of that symbol. Symbols reduce file size because, regardless of how many instances you've created, Flash stores only one copy of it in the file. Use symbols, animated or otherwise, for every element that appears more than once in a movie. You can modify the properties of an instance without affecting the master symbol, and edit the master symbol to change all instances.
When editing a symbol, both the Stage and the Timeline change to display the content of the symbol. You can change the Stage to display the symbol in isolation or in its current context by graying other items on the Stage. You can also edit the symbol in a separate window. The Timeline displays only the timeline of the symbol you are editing. For more information on symbols and instances, see Using symbols and instances overview.
Editing a symbol in isolation (left) and editing a symbol in its context in the movie.