When your published SWF files play on computers across the Internet, there is no guarantee that the fonts you used are available on those machines. To ensure that your text maintains the appearance you intended, you can embed entire fonts or specific subsets of characters from a font. By embedding the characters in your published SWF file, you make the font available to the SWF file regardless of the computer that plays the file. Once a font is embedded, you can use it anywhere in your published SWF file.
Beginning with Flash Professional CS5, Flash automatically embeds all characters used by any text objects that contain text. Creating an embedded font symbol yourself allows your text objects to use additional characters, such as when accepting user input at runtime or when editing text with ActionScript. Embedded fonts are not necessary for text objects that have the Anti-alias property set to Use Device Fonts. You specify which fonts you want embedded in your FLA file, and Flash embeds the fonts when you publish a SWF file.
There are 4 common situations in which to ensure correct text appearance by embedding fonts in a SWF file: