Colorwheel by Jonathan Whitfill
The spinning wait cursor or spinning disc pointer — where your mouse pointer becomes the rotating color wheel or "spinning beach ball" — generally indicates that your Mac is engaged in a processor-intensive activity. For example, applying a Gaussian blur to a raw file photograph for a class assignment due in 2 hours in Adobe Photoshop.
In most cases, the "beach ball" disappears within several seconds. However, there are cases when the "beach ball" spins protractedly, a condition colloquially known as "The Spinning Beach Ball of Death" (SBBOD).
Occasional appearances of the beach ball can be expected. Depending on your Mac's current workload, even common tasks may temporarily overtax your Mac's resources such as browsing your boyfriend's 4k song inventory on Itunes or trying to open a youtube window from Dlisted while also browsing huff po for real news.