I recommend checking out the copyright website section on Public Domain. It states, in part, that Internet works subject to copyright laws "include news, stories, sortware, novels, screenplays, graphics, pictures, and even email."

Also, checkout the U.S. Copyright Office Copyright Basics (Circular 1). Among many other things, it states that "Copyright is secured automatically when the work is created...."

While at the U.S. Copyright Office website, search for fair use. Fair use allows the limited use of copyrighted material, but is a rather gray area.