Aside from the legal and ethical issues regarding the unauthorized sharing of copyrighted material, there are some serious safety issues regarding these services. Some of the downloaded files — including photographs and videos — may be upsetting or harmful. It’s also a popular way for child molesters to exchange illegal images of children.

P2P file-sharing systems encourage users who download files to upload them as well. This may turn your PC into a server that shares your files, which can place you in legal trouble or possibly allow others to gain access to personal stuff on your computer. It’s like giving someone you don’t know the opportunity to know everything about you. It can also cause problems for other computers if you’re on a business, home, or school network.

Another problem with file-sharing services is the software used to access them can sometimes come with unwelcome extra “features” such as “spy ware” programs that can invade your privacy and display annoying advertising.

If you use a file-sharing service, be careful about what “permissions” you give when you set it up. Avoid sharing your own files and say no to any offers to install extra software. Even then, there is no guarantee you will not experience problems as a result of having the software on your computer.

• Anyone you don't know who asks you for personal information, photos or videos.
• Unsolicited obscene material from people or companies you don't know.
• Misleading URLs on the Internet that point you to sites containing harmful materials rather than what you were looking for.
• Anyone who wants to send you photos or videos containing obscene content of individuals 18 and younger. (The possession, manufacturing, or distributing of child pornography is illegal.)
• Online enticement for offline sexual activities. (No one should be making sexual invitations to you online – and it’s an especially serious crime for adults to do it.)