This is a Hashtag Activity Grid icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,300 icons, all in the same style and quality.
It's a logo on many small rectangles in a grid pattern. It should be four by four but in the lower left of the image the last rectangles of the lower two rows and half of the third rectangles of the lower two rows are covered by blank space and a hashtag image.
Related to Hashtag Activity Grid Icon
Related icons are the icons with matching tags, as well as all data icons. All icons are in the same flat style. You can either download free PNG icons or buy SVG vectors