CDA may refer to any of the following:
1. Short for Communication Decency Act. The CDA is an amendment to the U.S. 1996 Telecommunications Act that went into effect in February 1996. The law was intended to protect children from obscenity on the Internet, but many Internet users argued that its language was too vague and it violated the rights of free speech. Protesters against the law turned their web pages black and displayed blue ribbon icons downloaded from the Electronic Frontier Foundation.
2. Short for Compact Audio Disc, CDA (.cda) is an audio file type stored on CDs. CDA is the standard encoding format for commercial compact discs and may only be played through a CD-ROM.