I got a question about what the linking etiquette/law is when linking to online copyrighted material like the WSJ article and Redfin article on real estate photography. Is it legal to link to copyrighted material or quote copyrighted material or use charts from copyrighted material?
The law that deals with this subject is called "fair use". It generally says that:
Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, unlicensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test.
In other words it is legal and acceptable etiquette to:
I usually stop here although I notice that other blogs sometimes include as much as 10% or 25% of an article in a citation. In the end how far you go is a personal risk calculation. My approach is to do the two items above. So far no one has complained or asked me to take down a reference. You should know that in most website stats you can see every site that is linking to your content. So what you link to is visible to the owner of the site if they choose to see it.