VP8 and VP9 is an open video compression format used in WebM. It is released by Google but was originally created by On2 Technologies.
VP8 was originally designed to be the video format for HTML5. This version is used with Vorbis audio and placed in a WebM container.
WebP is a fixed image format derived from VP8.
VP9 is a successor to VP8 for WebM video for web browsers. Chromium, Chrome, Firefox, and Opera support playing VP9 video format in the HTML5 video tag. For WebM use this format uses Opus audio.
While WebM is considered as a video format it is really a container for various formats although all are based on the VP series video. WebM is an audio-video container format designed to provide royalty-free, open video compression for use with HTML5.
The WebM container is based on a profile of Matroska. WebM initially supported VP8 video and Vorbis audio streams. In 2013 it was updated to accommodate VP9 video and Opus audio as well.
Google's libvpx is currently the only encoder and main decoder for this format.
VP9 succeeds VP8 which was derived from VP7 which itself comes from VP6 (Used in FLV), VP5 and earlier VP3 used in Theora.
 For more information