The .flv file format stands for Flash Video. It is a container file format used to deliver video content over the Internet using Adobe Flash Player versions 6-11. Flash Video content can also be embedded within SWF files.

Here are some key points about the .flv file format:

1. Origin: Developed by Macromedia, which was acquired by Adobe Systems.
2. Use Case: Widely used for streaming video content on platforms such as YouTube, Hulu, and many other video-sharing sites before HTML5 video became the standard.
3. Content: Can contain synchronized audio and video streams. The video data in .flv files is usually encoded with the Sorenson Spark or VP6 codec, while the audio data is typically encoded as MP3, ADPCM, or AAC.
4. Structure:
   • Header: Contains metadata and is necessary to identify the file as an .flv file.
   • Body: Contains a sequence of tagged data, each tag having its own timestamp and payload data for audio, video, or metadata.
5. Advantages: Efficient streaming capabilities and wide compatibility with various browsers and devices when Flash Player was prevalent.
6. Disadvantages: Security vulnerabilities and performance issues led to its decline in popularity. Adobe ended support for Flash Player on December 31, 2020, prompting a shift to more modern formats like MP4 (using H.264 video codec and AAC audio codec).

Today, while .flv files may still be encountered, they are largely considered obsolete, with formats like MP4, WebM, and others preferred for video delivery on the web.