This Stream 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 4,900 icons, all in the same style and quality.
The icon is typically seen in loading animations for websites. It's a circle made up of smaller circles around the outside. One circle is larger, and they gradually get smaller as they progress around the outer circle.