Icons are pictorial representations of objects, important not only for aesthetic reasons as part of the visual identity of a program, but also for utilitarian reasons as shorthand for conveying meaning that users perceive almost instantaneously. Windows Vista introduces a new style of iconography that brings a higher level of detail and sophistication to Windows. Aero is the name for the user experience of Windows Vista, representing both the values embodied in the design of the aesthetics, as well as the vision behind the user interface (UI). Aero stands for: authentic, energetic, reflective, and open. Aero aims to establish a design that is both professional and beautiful. The Aero aesthetic creates a high quality and elegant experience that facilitates user productivity and even drives an emotional response. The following images depict what makes the Aero style of iconography in Windows Vista different from that used in Windows XP. The Windows Vista icons (the lock and key on the left) are authentic, crisp, and detailed. They are rendered rather than drawn, but are not completely photorealistic. The Windows Vista icons (the two on the left) are professional and beautiful, with attention to details that improve icon production quality. These Windows Vista icons show optical balance and perceived accuracy in perspective and details. This allows them to look great big or small, up-close or from a distance. Moreover, this style of iconography works for high-resolution screens. These examples show different types of icons, including a three-dimensional object in perspective, a front-facing (flat) icon, and a toolbar icon. These examples help demonstrate variations created based on the shape and position of the object itself. The shadow sometimes needs to be feathered or shortened to keep it from being cropped by the icon box size. The following tables show examples of scaling ratios applied to two common icon sizes. Note that not all of these sizes must be included in the .ico file. The code will scale larger ones down. At 16x16, the icon for the portable audio device could easily be mistaken for a cell phone—so the ear piece is a key visual detail to show. Note: For files without visually distinct content, don't use thumbnails. Instead, use traditional symbolic file icons showing object representation and the associated application or type. I'm designing an app for Windows 10 desktop and I need a simple list of icon sizes and the use of those sizes. Source.