What are these buttons, what is a bookmaklet?

• These buttons are bookmarklets. A bookmarklet is a special bookmark in your web browser that contains JavaScript commands.
• When you click on a bookmarklet the JavaScript code will run.
• Ninja uses bookmarklets to add a page to your collection or access your bookmarks in the browser.
• These bookmarklets are used only in the browsers of desktop computers (Windows and Mac). They are not used in mobile browsers.