This Loader icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 5,500 icons, all in the same style and quality.
The image is a circle made of circles. The circles vary in size. Starting from the bottom left is the smallest circle that looks like a dot. Going clockwise, the circles get bigger until the biggest one is right next to the dot at the bottom.