This Zakładka icon has Android KitKat style. If you use the icons for Android apps, we recommend using our latest Material Icons icon pack (please check our sidebar on the right). Otherwise, it's a solid icon pack that looks good in small resolutions, either on the web or in print. It's characterized by thick lines, smooth corners, and is optimized for 24x24 pixels.
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.