If your link brings the content of another site into your site through a frame, proceed with caution. Not only may you be involving trademark laws, but copyright laws as well.

In general terms, copyright is a group of rights that are owned by creators of original works such as stories, music, computer programs, choreography, drawings, movies, and many other things. Owners of copyrighted works have the exclusive right to prevent others from copying the work, distributing it to others, displaying or performing it to the public, or making new works from that original work.

Let's say you have links to various news agencies. When a user clicks on the link, a story from The New York Times appears on your site in your frame. That story belongs to the copyright owner-- and you may have just copied it and displayed it to the public without the owner's permission. This would be copyright infringement.

Or let's say you link to major movie studios who have trailers of upcoming movies. By clicking a link on your site, you bring that trailer into your site to view in one of your frames. It now appears as if it's on your site. Again, this may be copyright infringement of the trailer subjecting you to a civil lawsuit.