Other names for this bill...
This law usually is referred to by the acronym for Digital Millennium Copyright Act - DMCA.
Copyright protection
The stated purpose of the DMCA is to protect creative works.
The main provision of the law made it illegal to circumvent the digital locks on copyrighted music, movies, books, and software. But the wording is broad, and can prevent things that could be considered legitimate. For example, the law made it illegal to alter a cell phone that you own to allow it to run software not sanctioned by the manufacturer (a process known as jailbreaking or rooting).
Therefore, it allows the U.S. Copyright Office and the Library of Congress to grant exemptions.
Other provisions
Some other provisions of the DMCA...
o It protected the design of boats of specified sizes (Vessel Hull Design Protection Act).
Controversial uses of the DMCA
The DMCA has been used in extremely restrictive ways to stifle competition, research, and information detrimental to various companies.
The Electronic Frontier Foundation has documented such abuses in this 2013 report.
More information
You can find more details about this bill at GovTrack.us.