Peer-to-Peer (P2P) systems let users exchange files without them having a web site or other centralized system.

Initially the most famous of these services were used to share music files.
Now there are plenty of other P2P systems allowing users to exchange other types of files including...

• video;
• photographs;
• text documents; and
• software.

Apart from the legal and ethical issues regarding the unauthorized sharing of copyrighted material, there are some serious safety issues regarding these services.

Downloaded files...

• may be upsetting or harmful;
• are popular way for child molesters/pedophiles/sex offenders to exchange illegal images.

P2P file-sharing systems encourage users who download files to upload them as well; this may turn a users PC into a server...

• that shares their files;
  
• that place them in legal trouble; or
  
• that could allow others to gain access to personal stuff on the computer.