of service is distinct from Internet television, which involves third-party content over the public Internet not controlled by the local system operator. Features Programming features Electronic program guide Electronic program guides and interactive program guides provide users of television, radio, and other media applications with continuously updated menus displaying broadcast programming or scheduling information for current and upcoming programming. Some guides, such as ITV, also feature backward scrolling to promote their catch-up content. Favorites This feature allows the user to choose preferred channels, making them easier and quicker to access; this is handy with the wide range of digital channels on offer. The concept of favourite channels is superficially similar to that of the "bookmark" function offered in many Web browsers. Timer The timer allows the user to program and enable the box to switch between channels at certain times: this is handy to record from more than one channel while the user is out. The user still needs to program the VCR or DVD recorder. Convenience features Controls on the box Some models have controls on the box, as well as on the remote control. This is useful should the user lose the remote or if the batteries age. Remote controls that work with other TVs Some remote controls can also control some basic functions of various brands of TVs. This allows the user to use just one remote to turn the TV on and off, adjust volume, or switch between digital and analog TV channels or between terrestrial and internet channels. Parental locks The parental lock or content filters allow users over 18 years old to block access to channels that are not appropriate for children, using a personal identification number. Some boxes simply block all channels, while others allow the user to restrict access to chosen channels not suitable for children below certain ages. Software alternatives As complexity and potential programming faults of the set-top box increase, software such as MythTV, Select-TV and Microsoft's Media Center have developed features comparable to those of set-top boxes, ranging from basic DVR-like functionality to DVD copying, home automation, and housewide music or video playback. Firmware update features Almost all modern set-top boxes feature automatic firmware update processes. The firmware update is typically provided by the service provider. Ambiguities in the definition With the advent of flat-panel televisions, set-top boxes are now deeper in profile than the tops of most modern