Media player (application software) in the context of Media Player Classic

Windows Media Player (WMP, now officially referred to as Windows Media Player Legacy to distinguish it from the new Windows Media Player introduced with Windows 11) is the first media player and media library application that Microsoft developed to play audio and video on personal computers. It has been a component of the Microsoft Windows operating system, including Windows 9x, Windows NT, Pocket PC, and Windows Mobile. Microsoft also released editions of Windows Media Player for classic Mac OS, Mac OS X, and Solaris, but has since discontinued them.

In addition to being a media player, the app can rip audio file from compact discs, burn Audio CDs or MP3 CDs, synchronize content with a digital audio player or mobile devices, and stream media over the local network. Originally, it could connect to a number of digital music stores, allowing its users to purchase digital music. The default file formats are Windows Media Video (WMV), Windows Media Audio (WMA), and Advanced Systems Format (ASF), and its own XML based playlist format called Windows Playlist (WPL). The player is also able to utilize a digital rights management service in the form of Windows Media DRM.

MP1 (formally MPEG-1 Audio Layer I or MPEG-2 Audio Layer I) is a lossy audio codec and one of three audio formats included in the MPEG-1 standard. For files only containing MP1 audio, the file extension .mp1 is used.

It is a deliberately simplified version of MPEG-1 Audio Layer II, created for applications where lower compression efficiency could be tolerated in return for a less complex algorithm that could be executed with simpler hardware requirements. While supported by most media players, the codec is considered largely obsolete due to wider acceptance of the more complex MPEG-1 Audio Layer II (MP2) and MPEG-1 Audio Layer III (MP3) codecs.