Sentence:  I tiptoed over to Trent's nightstand and took his phone into the bathroom. I sat on the edge of the bathtub as I entered his code. When I saw that he'd changed his <WSD>screensaver</WSD> from our wedding picture to a picture of Diamond, my blood began to boil. I couldn't believe that he'd done that. 
Meaning of the word marked with <WSD> tags:  The background picture of a computer, smartphone, or similar mobile device.