Files with the extension .HME are 'theme' files used in conjunction with 'Windows Mobile SmartPhones'. A smartphone is described as being a mobile phone that offers capabilitites and features greater then that offered by a standard mobile phone, often with PC like functionality.

'Windows Mobile' is an operating system offering a suite of simple applications.

A .HME theme file contain the graphics/data for the modified theme i.e. wallpaper images, button,s icons, etc.