This is the most popular HTML5 audio playlist player and comes with tons of ready-to-use skins and presets! This versatile audio player offers a HUGE amount of customization and layout options. With basic css skills, players can be restyled into practically anything! Check out sample examples to get your imagination going.

1. Playlist Management: An audio player should allow users to create, edit, and manage playlists easily. Users can organize their music into different playlists for various moods or occasions.

2. Support for Multiple Audio Formats: A good audio player should support a wide range of audio file formats, including MP3, WAV, FLAC, AAC, and more.

3. Cross-Platform Compatibility: The ability to run on multiple operating systems and devices, such as Windows, macOS, iOS, Android, and even web browsers.

4. User-Friendly Interface: An intuitive and user-friendly interface with features like drag-and-drop for adding tracks to playlists and easy navigation.

5. Customization: Users should be able to customize the player's appearance, including themes, color schemes, and layout options.

6. Audio Equalizer: An equalizer with preset and custom settings to adjust the audio output according to the user's preferences.

7. Search and Sorting: Efficient search capabilities and sorting options for users to find their songs quickly.

8. Lyrics Display: Integration with online lyrics databases to display lyrics synchronized with the currently playing track.

9. Cover Art and Metadata: Automatic retrieval and display of album artwork and metadata for tracks.

10. Playback Controls: Standard controls for play, pause, skip, repeat, shuffle, and volume adjustment.

11. Offline Mode: Support for offline playback of downloaded songs.

12. Streaming Services Integration: Integration with popular music streaming services like Spotify, Apple Music, or YouTube for access to a broader music library.

13. Offline Library Management: Tools for managing and syncing offline music libraries, including album art and metadata.

14. Audio Bookmarks: The ability to set bookmarks or timestamps within a track for quick access to specific parts of a longer audio file, such as a podcast or audiobook.

15. Crossfade and Gapless Playback: Options to enable crossfade between songs and gapless playback for a smoother listening experience.

16. Playback History and Statistics: Keeping a history of recently played tracks and providing statistics on listening habits.

17. Remote Control and Casting: Support for remote control through mobile apps or casting to other devices.

18. Synchronization Across Devices: The ability to sync playlists, libraries, and settings across multiple devices.

19. Offline Music Syncing: Options to transfer and sync music files between devices.

20. Social Sharing: Integration with social media platforms to share what you're listening to.