You may ask: why do I care about Rear Yard. If you want to build an ADU, you may want to know. For Santa Clara, there is a limit of the how much the rear yard you can use for any structure.
For the city of Santa Clara, Rear Yard is defined in Santa Clara City Code for Rear Yard. Now that you know rear yard does not mean your backyard, you can take that information and incorporate into the equation for figuring out if you can, how big an ADU you can build, and how far back into the rear yard is allowed.