This is the Zakładka icon for Windows 10. Here we go. Optimized for 32x32 px, these are the simplest icons in the line style. Downloadable formats are PNG and SVG, among others. Icons8 icon pack is unique in providing a huge number of icons designed by the same team of four designers who create the new icons every working day in the same style and with the same quality. Same cool as the Bat Face, huh.
It's two pages of a book almost, if you were to take a piece of paper in the very middle and make an indentation as if it's curving inwards. Make those pieces inseparable, and then open it up to make a book thing. The purpose of the icon is to place a mark on a page, hence the name bookmark. It's a play on words mostly.