If an icon such as a paper clip or a color palete have a red background, that means there is a chart or a picture attached. Not loading lots of pictures and images all the time considerably speeds up your system and lets us make better use of your screen real estate. The red background lets you know to click on the icon if you want to view the image behind it.
For example you may not want to view a picture of the patient everytime you review their medical record, but it is there if you want it.